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Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
#include "cache/compressed_secondary_cache.h"
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
#include <array>
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
#include <iterator>
#include <memory>
#include <tuple>
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
#include "memory/jemalloc_nodump_allocator.h"
#include "rocksdb/convenience.h"
#include "test_util/secondary_cache_test_util.h"
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
#include "test_util/testharness.h"
#include "test_util/testutil.h"
namespace ROCKSDB_NAMESPACE {
using secondary_cache_test_util::GetHelper;
using secondary_cache_test_util::GetHelperFail;
using secondary_cache_test_util::TestCreateContext;
using secondary_cache_test_util::TestItem;
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
class CompressedSecondaryCacheTest : public testing::Test,
public TestCreateContext {
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
public:
CompressedSecondaryCacheTest() {}
~CompressedSecondaryCacheTest() override = default;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
protected:
void BasicTestHelper(std::shared_ptr<SecondaryCache> sec_cache,
bool sec_cache_is_compressed) {
get_perf_context()->Reset();
bool kept_in_sec_cache{true};
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Lookup an non-existent key.
std::unique_ptr<SecondaryCacheResultHandle> handle0 =
sec_cache->Lookup("k0", GetHelper(), this, true, /*advise_erase=*/true,
kept_in_sec_cache);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle0, nullptr);
Random rnd(301);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Insert and Lookup the item k1 for the first time.
std::string str1(rnd.RandomString(1000));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TestItem item1(str1.data(), str1.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// A dummy handle is inserted if the item is inserted for the first time.
ASSERT_OK(sec_cache->Insert("k1", &item1, GetHelper()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 1);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
std::unique_ptr<SecondaryCacheResultHandle> handle1_1 =
sec_cache->Lookup("k1", GetHelper(), this, true, /*advise_erase=*/false,
kept_in_sec_cache);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(handle1_1, nullptr);
// Insert and Lookup the item k1 for the second time and advise erasing it.
ASSERT_OK(sec_cache->Insert("k1", &item1, GetHelper()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 1);
std::unique_ptr<SecondaryCacheResultHandle> handle1_2 =
sec_cache->Lookup("k1", GetHelper(), this, true, /*advise_erase=*/true,
kept_in_sec_cache);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_NE(handle1_2, nullptr);
ASSERT_FALSE(kept_in_sec_cache);
if (sec_cache_is_compressed) {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes,
1000);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes,
1007);
} else {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
}
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
std::unique_ptr<TestItem> val1 =
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::unique_ptr<TestItem>(static_cast<TestItem*>(handle1_2->Value()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(val1, nullptr);
ASSERT_EQ(memcmp(val1->Buf(), item1.Buf(), item1.Size()), 0);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Lookup the item k1 again.
std::unique_ptr<SecondaryCacheResultHandle> handle1_3 =
sec_cache->Lookup("k1", GetHelper(), this, true, /*advise_erase=*/true,
kept_in_sec_cache);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(handle1_3, nullptr);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Insert and Lookup the item k2.
std::string str2(rnd.RandomString(1000));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TestItem item2(str2.data(), str2.length());
ASSERT_OK(sec_cache->Insert("k2", &item2, GetHelper()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 2);
std::unique_ptr<SecondaryCacheResultHandle> handle2_1 =
sec_cache->Lookup("k2", GetHelper(), this, true, /*advise_erase=*/false,
kept_in_sec_cache);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(handle2_1, nullptr);
ASSERT_OK(sec_cache->Insert("k2", &item2, GetHelper()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 2);
if (sec_cache_is_compressed) {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes,
2000);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes,
2014);
} else {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
}
std::unique_ptr<SecondaryCacheResultHandle> handle2_2 =
sec_cache->Lookup("k2", GetHelper(), this, true, /*advise_erase=*/false,
kept_in_sec_cache);
ASSERT_NE(handle2_2, nullptr);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
std::unique_ptr<TestItem> val2 =
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::unique_ptr<TestItem>(static_cast<TestItem*>(handle2_2->Value()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(val2, nullptr);
ASSERT_EQ(memcmp(val2->Buf(), item2.Buf(), item2.Size()), 0);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::vector<SecondaryCacheResultHandle*> handles = {handle1_2.get(),
handle2_2.get()};
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
sec_cache->WaitAll(handles);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
sec_cache.reset();
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
void BasicTest(bool sec_cache_is_compressed, bool use_jemalloc) {
CompressedSecondaryCacheOptions opts;
opts.capacity = 2048;
opts.num_shard_bits = 0;
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
opts.compression_type = CompressionType::kNoCompression;
sec_cache_is_compressed = false;
}
} else {
opts.compression_type = CompressionType::kNoCompression;
}
if (use_jemalloc) {
JemallocAllocatorOptions jopts;
std::shared_ptr<MemoryAllocator> allocator;
std::string msg;
if (JemallocNodumpAllocator::IsSupported(&msg)) {
Status s = NewJemallocNodumpAllocator(jopts, &allocator);
if (s.ok()) {
opts.memory_allocator = allocator;
}
} else {
ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
}
}
std::shared_ptr<SecondaryCache> sec_cache =
NewCompressedSecondaryCache(opts);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
BasicTestHelper(sec_cache, sec_cache_is_compressed);
}
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
void FailsTest(bool sec_cache_is_compressed) {
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
CompressedSecondaryCacheOptions secondary_cache_opts;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
} else {
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
secondary_cache_opts.capacity = 1100;
secondary_cache_opts.num_shard_bits = 0;
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
std::shared_ptr<SecondaryCache> sec_cache =
NewCompressedSecondaryCache(secondary_cache_opts);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Insert and Lookup the first item.
Random rnd(301);
std::string str1(rnd.RandomString(1000));
TestItem item1(str1.data(), str1.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Insert a dummy handle.
ASSERT_OK(sec_cache->Insert("k1", &item1, GetHelper()));
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Insert k1.
ASSERT_OK(sec_cache->Insert("k1", &item1, GetHelper()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Insert and Lookup the second item.
std::string str2(rnd.RandomString(200));
TestItem item2(str2.data(), str2.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Insert a dummy handle, k1 is not evicted.
ASSERT_OK(sec_cache->Insert("k2", &item2, GetHelper()));
bool kept_in_sec_cache{false};
std::unique_ptr<SecondaryCacheResultHandle> handle1 =
sec_cache->Lookup("k1", GetHelper(), this, true, /*advise_erase=*/false,
kept_in_sec_cache);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(handle1, nullptr);
// Insert k2 and k1 is evicted.
ASSERT_OK(sec_cache->Insert("k2", &item2, GetHelper()));
std::unique_ptr<SecondaryCacheResultHandle> handle2 =
sec_cache->Lookup("k2", GetHelper(), this, true, /*advise_erase=*/false,
kept_in_sec_cache);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle2, nullptr);
std::unique_ptr<TestItem> val2 =
std::unique_ptr<TestItem>(static_cast<TestItem*>(handle2->Value()));
ASSERT_NE(val2, nullptr);
ASSERT_EQ(memcmp(val2->Buf(), item2.Buf(), item2.Size()), 0);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Insert k1 again and a dummy handle is inserted.
ASSERT_OK(sec_cache->Insert("k1", &item1, GetHelper()));
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::unique_ptr<SecondaryCacheResultHandle> handle1_1 =
sec_cache->Lookup("k1", GetHelper(), this, true, /*advise_erase=*/false,
kept_in_sec_cache);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(handle1_1, nullptr);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Create Fails.
SetFailCreate(true);
std::unique_ptr<SecondaryCacheResultHandle> handle2_1 =
sec_cache->Lookup("k2", GetHelper(), this, true, /*advise_erase=*/true,
kept_in_sec_cache);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle2_1, nullptr);
// Save Fails.
std::string str3 = rnd.RandomString(10);
TestItem item3(str3.data(), str3.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// The Status is OK because a dummy handle is inserted.
ASSERT_OK(sec_cache->Insert("k3", &item3, GetHelperFail()));
ASSERT_NOK(sec_cache->Insert("k3", &item3, GetHelperFail()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
sec_cache.reset();
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
void BasicIntegrationTest(bool sec_cache_is_compressed,
bool enable_custom_split_merge) {
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
CompressedSecondaryCacheOptions secondary_cache_opts;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
sec_cache_is_compressed = false;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
} else {
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
secondary_cache_opts.capacity = 6000;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
secondary_cache_opts.num_shard_bits = 0;
secondary_cache_opts.enable_custom_split_merge = enable_custom_split_merge;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
std::shared_ptr<SecondaryCache> secondary_cache =
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
NewCompressedSecondaryCache(secondary_cache_opts);
LRUCacheOptions lru_cache_opts(
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
/*_capacity =*/1300, /*_num_shard_bits =*/0,
/*_strict_capacity_limit =*/false, /*_high_pri_pool_ratio =*/0.5,
/*_memory_allocator =*/nullptr, kDefaultToAdaptiveMutex,
kDefaultCacheMetadataChargePolicy, /*_low_pri_pool_ratio =*/0.0);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
lru_cache_opts.secondary_cache = secondary_cache;
std::shared_ptr<Cache> cache = NewLRUCache(lru_cache_opts);
std::shared_ptr<Statistics> stats = CreateDBStatistics();
get_perf_context()->Reset();
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Random rnd(301);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str1 = rnd.RandomString(1001);
auto item1_1 = new TestItem(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1_1, GetHelper(), str1.length()));
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str2 = rnd.RandomString(1012);
auto item2_1 = new TestItem(str2.data(), str2.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k2 and secondary cache contains
// k1's dummy item.
ASSERT_OK(cache->Insert("k2", item2_1, GetHelper(), str2.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 1);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str3 = rnd.RandomString(1024);
auto item3_1 = new TestItem(str3.data(), str3.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k3 and secondary cache contains
// k1's dummy item and k2's dummy item.
ASSERT_OK(cache->Insert("k3", item3_1, GetHelper(), str3.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 2);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k1 and secondary cache contains
// k1's dummy item, k2's dummy item, and k3's dummy item.
auto item1_2 = new TestItem(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1_2, GetHelper(), str1.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 3);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k2 and secondary cache contains
// k1's item, k2's dummy item, and k3's dummy item.
auto item2_2 = new TestItem(str2.data(), str2.length());
ASSERT_OK(cache->Insert("k2", item2_2, GetHelper(), str2.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 1);
if (sec_cache_is_compressed) {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes,
str1.length());
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes,
1008);
} else {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
}
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k3 and secondary cache contains
// k1's item and k2's item.
auto item3_2 = new TestItem(str3.data(), str3.length());
ASSERT_OK(cache->Insert("k3", item3_2, GetHelper(), str3.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 2);
if (sec_cache_is_compressed) {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes,
str1.length() + str2.length());
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes,
2027);
} else {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
}
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Cache::Handle* handle;
handle = cache->Lookup("k3", GetHelper(), this, Cache::Priority::LOW, true,
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
stats.get());
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle, nullptr);
auto val3 = static_cast<TestItem*>(cache->Value(handle));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(val3, nullptr);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(memcmp(val3->Buf(), item3_2->Buf(), item3_2->Size()), 0);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
cache->Release(handle);
// Lookup an non-existent key.
handle = cache->Lookup("k0", GetHelper(), this, Cache::Priority::LOW, true,
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
stats.get());
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle, nullptr);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// This Lookup should just insert a dummy handle in the primary cache
// and the k1 is still in the secondary cache.
handle = cache->Lookup("k1", GetHelper(), this, Cache::Priority::LOW, true,
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
stats.get());
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle, nullptr);
ASSERT_EQ(get_perf_context()->block_cache_standalone_handle_count, 1);
auto val1_1 = static_cast<TestItem*>(cache->Value(handle));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(val1_1, nullptr);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
ASSERT_EQ(memcmp(val1_1->Buf(), str1.data(), str1.size()), 0);
cache->Release(handle);
// This Lookup should erase k1 from the secondary cache and insert
// it into primary cache; then k3 is demoted.
// k2 and k3 are in secondary cache.
handle = cache->Lookup("k1", GetHelper(), this, Cache::Priority::LOW, true,
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
stats.get());
ASSERT_NE(handle, nullptr);
ASSERT_EQ(get_perf_context()->block_cache_standalone_handle_count, 1);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 3);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
cache->Release(handle);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// k2 is still in secondary cache.
handle = cache->Lookup("k2", GetHelper(), this, Cache::Priority::LOW, true,
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
stats.get());
ASSERT_NE(handle, nullptr);
ASSERT_EQ(get_perf_context()->block_cache_standalone_handle_count, 2);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
cache->Release(handle);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Testing SetCapacity().
ASSERT_OK(secondary_cache->SetCapacity(0));
handle = cache->Lookup("k3", GetHelper(), this, Cache::Priority::LOW, true,
stats.get());
ASSERT_EQ(handle, nullptr);
ASSERT_OK(secondary_cache->SetCapacity(7000));
size_t capacity;
ASSERT_OK(secondary_cache->GetCapacity(capacity));
ASSERT_EQ(capacity, 7000);
auto item1_3 = new TestItem(str1.data(), str1.length());
// After this Insert, primary cache contains k1.
ASSERT_OK(cache->Insert("k1", item1_3, GetHelper(), str2.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 3);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 4);
auto item2_3 = new TestItem(str2.data(), str2.length());
// After this Insert, primary cache contains k2 and secondary cache contains
// k1's dummy item.
ASSERT_OK(cache->Insert("k2", item2_3, GetHelper(), str1.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 4);
auto item1_4 = new TestItem(str1.data(), str1.length());
// After this Insert, primary cache contains k1 and secondary cache contains
// k1's dummy item and k2's dummy item.
ASSERT_OK(cache->Insert("k1", item1_4, GetHelper(), str2.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 5);
auto item2_4 = new TestItem(str2.data(), str2.length());
// After this Insert, primary cache contains k2 and secondary cache contains
// k1's real item and k2's dummy item.
ASSERT_OK(cache->Insert("k2", item2_4, GetHelper(), str2.length()));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 5);
// This Lookup should just insert a dummy handle in the primary cache
// and the k1 is still in the secondary cache.
handle = cache->Lookup("k1", GetHelper(), this, Cache::Priority::LOW, true,
stats.get());
ASSERT_NE(handle, nullptr);
cache->Release(handle);
ASSERT_EQ(get_perf_context()->block_cache_standalone_handle_count, 3);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
cache.reset();
secondary_cache.reset();
}
void BasicIntegrationFailTest(bool sec_cache_is_compressed) {
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
CompressedSecondaryCacheOptions secondary_cache_opts;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
} else {
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
secondary_cache_opts.capacity = 6000;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
secondary_cache_opts.num_shard_bits = 0;
std::shared_ptr<SecondaryCache> secondary_cache =
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
NewCompressedSecondaryCache(secondary_cache_opts);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
LRUCacheOptions opts(
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
/*_capacity=*/1300, /*_num_shard_bits=*/0,
/*_strict_capacity_limit=*/false, /*_high_pri_pool_ratio=*/0.5,
/*_memory_allocator=*/nullptr, kDefaultToAdaptiveMutex,
kDefaultCacheMetadataChargePolicy, /*_low_pri_pool_ratio=*/0.0);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
opts.secondary_cache = secondary_cache;
std::shared_ptr<Cache> cache = NewLRUCache(opts);
Random rnd(301);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str1 = rnd.RandomString(1001);
auto item1 = std::make_unique<TestItem>(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1.get(), GetHelper(), str1.length()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
item1.release(); // Appease clang-analyze "potential memory leak"
Cache::Handle* handle;
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
handle = cache->Lookup("k2", nullptr, this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle, nullptr);
handle =
cache->Lookup("k2", GetHelper(), this, Cache::Priority::LOW, false);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle, nullptr);
cache.reset();
secondary_cache.reset();
}
void IntegrationSaveFailTest(bool sec_cache_is_compressed) {
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
CompressedSecondaryCacheOptions secondary_cache_opts;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
} else {
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
secondary_cache_opts.capacity = 6000;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
secondary_cache_opts.num_shard_bits = 0;
std::shared_ptr<SecondaryCache> secondary_cache =
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
NewCompressedSecondaryCache(secondary_cache_opts);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
LRUCacheOptions opts(
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
/*_capacity=*/1300, /*_num_shard_bits=*/0,
/*_strict_capacity_limit=*/false, /*_high_pri_pool_ratio=*/0.5,
/*_memory_allocator=*/nullptr, kDefaultToAdaptiveMutex,
kDefaultCacheMetadataChargePolicy, /*_low_pri_pool_ratio=*/0.0);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
opts.secondary_cache = secondary_cache;
std::shared_ptr<Cache> cache = NewLRUCache(opts);
Random rnd(301);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str1 = rnd.RandomString(1001);
auto item1 = new TestItem(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1, GetHelperFail(), str1.length()));
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str2 = rnd.RandomString(1002);
auto item2 = new TestItem(str2.data(), str2.length());
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// k1 should be demoted to the secondary cache.
ASSERT_OK(cache->Insert("k2", item2, GetHelperFail(), str2.length()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Cache::Handle* handle;
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
handle =
cache->Lookup("k2", GetHelperFail(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle, nullptr);
cache->Release(handle);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// This lookup should fail, since k1 demotion would have failed.
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
handle =
cache->Lookup("k1", GetHelperFail(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle, nullptr);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// Since k1 was not promoted, k2 should still be in cache.
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
handle =
cache->Lookup("k2", GetHelperFail(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle, nullptr);
cache->Release(handle);
cache.reset();
secondary_cache.reset();
}
void IntegrationCreateFailTest(bool sec_cache_is_compressed) {
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
CompressedSecondaryCacheOptions secondary_cache_opts;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
} else {
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
secondary_cache_opts.capacity = 6000;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
secondary_cache_opts.num_shard_bits = 0;
std::shared_ptr<SecondaryCache> secondary_cache =
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
NewCompressedSecondaryCache(secondary_cache_opts);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
LRUCacheOptions opts(
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
/*_capacity=*/1300, /*_num_shard_bits=*/0,
/*_strict_capacity_limit=*/false, /*_high_pri_pool_ratio=*/0.5,
/*_memory_allocator=*/nullptr, kDefaultToAdaptiveMutex,
kDefaultCacheMetadataChargePolicy, /*_low_pri_pool_ratio=*/0.0);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
opts.secondary_cache = secondary_cache;
std::shared_ptr<Cache> cache = NewLRUCache(opts);
Random rnd(301);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str1 = rnd.RandomString(1001);
auto item1 = new TestItem(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1, GetHelper(), str1.length()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str2 = rnd.RandomString(1002);
auto item2 = new TestItem(str2.data(), str2.length());
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// k1 should be demoted to the secondary cache.
ASSERT_OK(cache->Insert("k2", item2, GetHelper(), str2.length()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Cache::Handle* handle;
SetFailCreate(true);
handle = cache->Lookup("k2", GetHelper(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle, nullptr);
cache->Release(handle);
// This lookup should fail, since k1 creation would have failed
handle = cache->Lookup("k1", GetHelper(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_EQ(handle, nullptr);
// Since k1 didn't get promoted, k2 should still be in cache
handle = cache->Lookup("k2", GetHelper(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle, nullptr);
cache->Release(handle);
cache.reset();
secondary_cache.reset();
}
void IntegrationFullCapacityTest(bool sec_cache_is_compressed) {
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
CompressedSecondaryCacheOptions secondary_cache_opts;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
if (sec_cache_is_compressed) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
} else {
secondary_cache_opts.compression_type = CompressionType::kNoCompression;
}
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
secondary_cache_opts.capacity = 6000;
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
secondary_cache_opts.num_shard_bits = 0;
std::shared_ptr<SecondaryCache> secondary_cache =
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
NewCompressedSecondaryCache(secondary_cache_opts);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
LRUCacheOptions opts(
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
/*_capacity=*/1300, /*_num_shard_bits=*/0,
/*_strict_capacity_limit=*/false, /*_high_pri_pool_ratio=*/0.5,
/*_memory_allocator=*/nullptr, kDefaultToAdaptiveMutex,
kDefaultCacheMetadataChargePolicy, /*_low_pri_pool_ratio=*/0.0);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
opts.secondary_cache = secondary_cache;
std::shared_ptr<Cache> cache = NewLRUCache(opts);
Random rnd(301);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str1 = rnd.RandomString(1001);
auto item1_1 = new TestItem(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1_1, GetHelper(), str1.length()));
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
std::string str2 = rnd.RandomString(1002);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
std::string str2_clone{str2};
auto item2 = new TestItem(str2.data(), str2.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k2 and secondary cache contains
// k1's dummy item.
ASSERT_OK(cache->Insert("k2", item2, GetHelper(), str2.length()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k1 and secondary cache contains
// k1's dummy item and k2's dummy item.
auto item1_2 = new TestItem(str1.data(), str1.length());
ASSERT_OK(cache->Insert("k1", item1_2, GetHelper(), str1.length()));
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
auto item2_2 = new TestItem(str2.data(), str2.length());
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// After this Insert, primary cache contains k2 and secondary cache contains
// k1's item and k2's dummy item.
ASSERT_OK(cache->Insert("k2", item2_2, GetHelper(), str2.length()));
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Cache::Handle* handle2;
handle2 =
cache->Lookup("k2", GetHelper(), this, Cache::Priority::LOW, true);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
ASSERT_NE(handle2, nullptr);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
cache->Release(handle2);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
// k1 promotion should fail because cache is at capacity and
// strict_capacity_limit is true, but the lookup should still succeed.
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
// A k1's dummy item is inserted into primary cache.
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
Cache::Handle* handle1;
handle1 =
cache->Lookup("k1", GetHelper(), this, Cache::Priority::LOW, true);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
ASSERT_NE(handle1, nullptr);
cache->Release(handle1);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
// Since k1 didn't get inserted, k2 should still be in cache
handle2 =
cache->Lookup("k2", GetHelper(), this, Cache::Priority::LOW, true);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
ASSERT_NE(handle2, nullptr);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
cache->Release(handle2);
cache.reset();
secondary_cache.reset();
}
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
void SplitValueIntoChunksTest() {
JemallocAllocatorOptions jopts;
std::shared_ptr<MemoryAllocator> allocator;
std::string msg;
if (JemallocNodumpAllocator::IsSupported(&msg)) {
Status s = NewJemallocNodumpAllocator(jopts, &allocator);
if (!s.ok()) {
ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
}
} else {
ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
}
using CacheValueChunk = CompressedSecondaryCache::CacheValueChunk;
std::unique_ptr<CompressedSecondaryCache> sec_cache =
std::make_unique<CompressedSecondaryCache>(1000, 0, true, 0.5, 0.0,
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
allocator);
Random rnd(301);
// 8500 = 8169 + 233 + 98, so there should be 3 chunks after split.
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
size_t str_size{8500};
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
std::string str = rnd.RandomString(static_cast<int>(str_size));
size_t charge{0};
CacheValueChunk* chunks_head =
sec_cache->SplitValueIntoChunks(str, kLZ4Compression, charge);
ASSERT_EQ(charge, str_size + 3 * (sizeof(CacheValueChunk) - 1));
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
CacheValueChunk* current_chunk = chunks_head;
ASSERT_EQ(current_chunk->size, 8192 - sizeof(CacheValueChunk) + 1);
current_chunk = current_chunk->next;
ASSERT_EQ(current_chunk->size, 256 - sizeof(CacheValueChunk) + 1);
current_chunk = current_chunk->next;
ASSERT_EQ(current_chunk->size, 98);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
sec_cache->GetHelper(true)->del_cb(chunks_head, /*alloc*/ nullptr);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
}
void MergeChunksIntoValueTest() {
using CacheValueChunk = CompressedSecondaryCache::CacheValueChunk;
Random rnd(301);
size_t size1{2048};
std::string str1 = rnd.RandomString(static_cast<int>(size1));
Fix the segdefault bug in CompressedSecondaryCache and its tests (#10507) Summary: This fix is to replace `AllocateBlock()` with `new`. Once I figure out why `AllocateBlock()` might cause the segfault, I will update the implementation. Fix the bug that causes ./compressed_secondary_cache_test output following test failures: ``` Note: Google Test filter = CompressedSecondaryCacheTest.MergeChunksIntoValueTest [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from CompressedSecondaryCacheTest [ RUN ] CompressedSecondaryCacheTest.MergeChunksIntoValueTest [ OK ] CompressedSecondaryCacheTest.MergeChunksIntoValueTest (1 ms) [----------] 1 test from CompressedSecondaryCacheTest (1 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (9 ms total) [ PASSED ] 1 test. t/run-compressed_secondary_cache_test-CompressedSecondaryCacheTest.MergeChunksIntoValueTest: line 4: 1091086 Segmentation fault (core dumped) TEST_TMPDIR=$d ./compressed_secondary_cache_test --gtest_filter=CompressedSecondaryCacheTest.MergeChunksIntoValueTest Note: Google Test filter = CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from CompressedSecondaryCacheTest [ RUN ] CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression [ OK ] CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression (1 ms) [----------] 1 test from CompressedSecondaryCacheTest (1 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (2 ms total) [ PASSED ] 1 test. t/run-compressed_secondary_cache_test-CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression: line 4: 1090883 Segmentation fault (core dumped) TEST_TMPDIR=$d ./compressed_secondary_cache_test --gtest_filter=CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/10507 Test Plan: Test 1: ``` $make -j 24 $./compressed_secondary_cache_test ``` Test 2: ``` $COMPILE_WITH_ASAN=1 make -j 24 $./compressed_secondary_cache_test ``` Test 3: ``` $COMPILE_WITH_TSAN=1 make -j 24 $./compressed_secondary_cache_test ``` Reviewed By: anand1976 Differential Revision: D38529885 Pulled By: gitbw95 fbshipit-source-id: d903fa3fadbd4d29f9528728c63a4f61c4396890
2 years ago
CacheValueChunk* current_chunk = reinterpret_cast<CacheValueChunk*>(
new char[sizeof(CacheValueChunk) - 1 + size1]);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
CacheValueChunk* chunks_head = current_chunk;
memcpy(current_chunk->data, str1.data(), size1);
current_chunk->size = size1;
size_t size2{256};
std::string str2 = rnd.RandomString(static_cast<int>(size2));
Fix the segdefault bug in CompressedSecondaryCache and its tests (#10507) Summary: This fix is to replace `AllocateBlock()` with `new`. Once I figure out why `AllocateBlock()` might cause the segfault, I will update the implementation. Fix the bug that causes ./compressed_secondary_cache_test output following test failures: ``` Note: Google Test filter = CompressedSecondaryCacheTest.MergeChunksIntoValueTest [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from CompressedSecondaryCacheTest [ RUN ] CompressedSecondaryCacheTest.MergeChunksIntoValueTest [ OK ] CompressedSecondaryCacheTest.MergeChunksIntoValueTest (1 ms) [----------] 1 test from CompressedSecondaryCacheTest (1 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (9 ms total) [ PASSED ] 1 test. t/run-compressed_secondary_cache_test-CompressedSecondaryCacheTest.MergeChunksIntoValueTest: line 4: 1091086 Segmentation fault (core dumped) TEST_TMPDIR=$d ./compressed_secondary_cache_test --gtest_filter=CompressedSecondaryCacheTest.MergeChunksIntoValueTest Note: Google Test filter = CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from CompressedSecondaryCacheTest [ RUN ] CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression [ OK ] CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression (1 ms) [----------] 1 test from CompressedSecondaryCacheTest (1 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (2 ms total) [ PASSED ] 1 test. t/run-compressed_secondary_cache_test-CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression: line 4: 1090883 Segmentation fault (core dumped) TEST_TMPDIR=$d ./compressed_secondary_cache_test --gtest_filter=CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/10507 Test Plan: Test 1: ``` $make -j 24 $./compressed_secondary_cache_test ``` Test 2: ``` $COMPILE_WITH_ASAN=1 make -j 24 $./compressed_secondary_cache_test ``` Test 3: ``` $COMPILE_WITH_TSAN=1 make -j 24 $./compressed_secondary_cache_test ``` Reviewed By: anand1976 Differential Revision: D38529885 Pulled By: gitbw95 fbshipit-source-id: d903fa3fadbd4d29f9528728c63a4f61c4396890
2 years ago
current_chunk->next = reinterpret_cast<CacheValueChunk*>(
new char[sizeof(CacheValueChunk) - 1 + size2]);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
current_chunk = current_chunk->next;
memcpy(current_chunk->data, str2.data(), size2);
current_chunk->size = size2;
size_t size3{31};
std::string str3 = rnd.RandomString(static_cast<int>(size3));
Fix the segdefault bug in CompressedSecondaryCache and its tests (#10507) Summary: This fix is to replace `AllocateBlock()` with `new`. Once I figure out why `AllocateBlock()` might cause the segfault, I will update the implementation. Fix the bug that causes ./compressed_secondary_cache_test output following test failures: ``` Note: Google Test filter = CompressedSecondaryCacheTest.MergeChunksIntoValueTest [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from CompressedSecondaryCacheTest [ RUN ] CompressedSecondaryCacheTest.MergeChunksIntoValueTest [ OK ] CompressedSecondaryCacheTest.MergeChunksIntoValueTest (1 ms) [----------] 1 test from CompressedSecondaryCacheTest (1 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (9 ms total) [ PASSED ] 1 test. t/run-compressed_secondary_cache_test-CompressedSecondaryCacheTest.MergeChunksIntoValueTest: line 4: 1091086 Segmentation fault (core dumped) TEST_TMPDIR=$d ./compressed_secondary_cache_test --gtest_filter=CompressedSecondaryCacheTest.MergeChunksIntoValueTest Note: Google Test filter = CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from CompressedSecondaryCacheTest [ RUN ] CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression [ OK ] CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression (1 ms) [----------] 1 test from CompressedSecondaryCacheTest (1 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (2 ms total) [ PASSED ] 1 test. t/run-compressed_secondary_cache_test-CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression: line 4: 1090883 Segmentation fault (core dumped) TEST_TMPDIR=$d ./compressed_secondary_cache_test --gtest_filter=CompressedSecondaryCacheTest.BasicTestWithMemoryAllocatorAndCompression ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/10507 Test Plan: Test 1: ``` $make -j 24 $./compressed_secondary_cache_test ``` Test 2: ``` $COMPILE_WITH_ASAN=1 make -j 24 $./compressed_secondary_cache_test ``` Test 3: ``` $COMPILE_WITH_TSAN=1 make -j 24 $./compressed_secondary_cache_test ``` Reviewed By: anand1976 Differential Revision: D38529885 Pulled By: gitbw95 fbshipit-source-id: d903fa3fadbd4d29f9528728c63a4f61c4396890
2 years ago
current_chunk->next = reinterpret_cast<CacheValueChunk*>(
new char[sizeof(CacheValueChunk) - 1 + size3]);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
current_chunk = current_chunk->next;
memcpy(current_chunk->data, str3.data(), size3);
current_chunk->size = size3;
current_chunk->next = nullptr;
std::string str = str1 + str2 + str3;
std::unique_ptr<CompressedSecondaryCache> sec_cache =
std::make_unique<CompressedSecondaryCache>(1000, 0, true, 0.5, 0.0);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
size_t charge{0};
CacheAllocationPtr value =
sec_cache->MergeChunksIntoValue(chunks_head, charge);
ASSERT_EQ(charge, size1 + size2 + size3);
std::string value_str{value.get(), charge};
ASSERT_EQ(strcmp(value_str.data(), str.data()), 0);
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
while (chunks_head != nullptr) {
CacheValueChunk* tmp_chunk = chunks_head;
chunks_head = chunks_head->next;
tmp_chunk->Free();
}
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
}
void SplictValueAndMergeChunksTest() {
JemallocAllocatorOptions jopts;
std::shared_ptr<MemoryAllocator> allocator;
std::string msg;
if (JemallocNodumpAllocator::IsSupported(&msg)) {
Status s = NewJemallocNodumpAllocator(jopts, &allocator);
if (!s.ok()) {
ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
}
} else {
ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
}
using CacheValueChunk = CompressedSecondaryCache::CacheValueChunk;
std::unique_ptr<CompressedSecondaryCache> sec_cache =
std::make_unique<CompressedSecondaryCache>(1000, 0, true, 0.5, 0.0,
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
allocator);
Random rnd(301);
// 8500 = 8169 + 233 + 98, so there should be 3 chunks after split.
Avoid recompressing cold block in CompressedSecondaryCache (#10527) Summary: **Summary:** When a block is firstly `Lookup` from the secondary cache, we just insert a dummy block in the primary cache (charging the actual size of the block) and don’t erase the block from the secondary cache. A standalone handle is returned from `Lookup`. Only if the block is hit again, we erase it from the secondary cache and add it into the primary cache. When a block is firstly evicted from the primary cache to the secondary cache, we just insert a dummy block (size 0) in the secondary cache. When the block is evicted again, it is treated as a hot block and is inserted into the secondary cache. **Implementation Details** Add a new state of LRUHandle: The handle is never inserted into the LRUCache (both hash table and LRU list) and it doesn't experience the above three states. The entry can be freed when refs becomes 0. (refs >= 1 && in_cache == false && IS_STANDALONE == true) The behaviors of `LRUCacheShard::Lookup()` are updated if the secondary_cache is CompressedSecondaryCache: 1. If a handle is found in primary cache: 1.1. If the handle's value is not nullptr, it is returned immediately. 1.2. If the handle's value is nullptr, this means the handle is a dummy one. For a dummy handle, if it was retrieved from secondary cache, it may still exist in secondary cache. - 1.2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. - 1.2.2. If the handle from secondary cache is valid, erase it from the secondary cache and add it into the primary cache. 2. If a handle is not found in primary cache: 2.1. If no valid handle can be `Lookup` from secondary cache, return nullptr. 2.2. If the handle from secondary cache is valid, insert a dummy block in the primary cache (charging the actual size of the block) and return a standalone handle. The behaviors of `LRUCacheShard::Promote()` are updated as follows: 1. If `e->sec_handle` has value, one of the following steps can happen: 1.1. Insert a dummy handle and return a standalone handle to caller when `secondary_cache_` is `CompressedSecondaryCache` and e is a standalone handle. 1.2. Insert the item into the primary cache and return the handle to caller. 1.3. Exception handling. 3. If `e->sec_handle` has no value, mark the item as not in cache and charge the cache as its only metadata that'll shortly be released. The behavior of `CompressedSecondaryCache::Insert()` is updated: 1. If a block is evicted from the primary cache for the first time, a dummy item is inserted. 4. If a dummy item is found for a block, the block is inserted into the secondary cache. The behavior of `CompressedSecondaryCache:::Lookup()` is updated: 1. If a handle is not found or it is a dummy item, a nullptr is returned. 2. If `erase_handle` is true, the handle is erased. The behaviors of `LRUCacheShard::Release()` are adjusted for the standalone handles. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10527 Test Plan: 1. stress tests. 5. unit tests. 6. CPU profiling for db_bench. Reviewed By: siying Differential Revision: D38747613 Pulled By: gitbw95 fbshipit-source-id: 74a1eba7e1957c9affb2bd2ae3e0194584fa6eca
2 years ago
size_t str_size{8500};
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
std::string str = rnd.RandomString(static_cast<int>(str_size));
size_t charge{0};
CacheValueChunk* chunks_head =
sec_cache->SplitValueIntoChunks(str, kLZ4Compression, charge);
ASSERT_EQ(charge, str_size + 3 * (sizeof(CacheValueChunk) - 1));
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
CacheAllocationPtr value =
sec_cache->MergeChunksIntoValue(chunks_head, charge);
ASSERT_EQ(charge, str_size);
std::string value_str{value.get(), charge};
ASSERT_EQ(strcmp(value_str.data(), str.data()), 0);
Major Cache refactoring, CPU efficiency improvement (#10975) Summary: This is several refactorings bundled into one to avoid having to incrementally re-modify uses of Cache several times. Overall, there are breaking changes to Cache class, and it becomes more of low-level interface for implementing caches, especially block cache. New internal APIs make using Cache cleaner than before, and more insulated from block cache evolution. Hopefully, this is the last really big block cache refactoring, because of rather effectively decoupling the implementations from the uses. This change also removes the EXPERIMENTAL designation on the SecondaryCache support in Cache. It seems reasonably mature at this point but still subject to change/evolution (as I warn in the API docs for Cache). The high-level motivation for this refactoring is to minimize code duplication / compounding complexity in adding SecondaryCache support to HyperClockCache (in a later PR). Other benefits listed below. * static_cast lines of code +29 -35 (net removed 6) * reinterpret_cast lines of code +6 -32 (net removed 26) ## cache.h and secondary_cache.h * Always use CacheItemHelper with entries instead of just a Deleter. There are several motivations / justifications: * Simpler for implementations to deal with just one Insert and one Lookup. * Simpler and more efficient implementation because we don't have to track which entries are using helpers and which are using deleters * Gets rid of hack to classify cache entries by their deleter. Instead, the CacheItemHelper includes a CacheEntryRole. This simplifies a lot of code (cache_entry_roles.h almost eliminated). Fixes https://github.com/facebook/rocksdb/issues/9428. * Makes it trivial to adjust SecondaryCache behavior based on kind of block (e.g. don't re-compress filter blocks). * It is arguably less convenient for many direct users of Cache, but direct users of Cache are now rare with introduction of typed_cache.h (below). * I considered and rejected an alternative approach in which we reduce customizability by assuming each secondary cache compatible value starts with a Slice referencing the uncompressed block contents (already true or mostly true), but we apparently intend to stack secondary caches. Saving an entry from a compressed secondary to a lower tier requires custom handling offered by SaveToCallback, etc. * Make CreateCallback part of the helper and introduce CreateContext to work with it (alternative to https://github.com/facebook/rocksdb/issues/10562). This cleans up the interface while still allowing context to be provided for loading/parsing values into primary cache. This model works for async lookup in BlockBasedTable reader (reader owns a CreateContext) under the assumption that it always waits on secondary cache operations to finish. (Otherwise, the CreateContext could be destroyed while async operation depending on it continues.) This likely contributes most to the observed performance improvement because it saves an std::function backed by a heap allocation. * Use char* for serialized data, e.g. in SaveToCallback, where void* was confusingly used. (We use `char*` for serialized byte data all over RocksDB, with many advantages over `void*`. `memcpy` etc. are legacy APIs that should not be mimicked.) * Add a type alias Cache::ObjectPtr = void*, so that we can better indicate the intent of the void* when it is to be the object associated with a Cache entry. Related: started (but did not complete) a refactoring to move away from "value" of a cache entry toward "object" or "obj". (It is confusing to call Cache a key-value store (like DB) when it is really storing arbitrary in-memory objects, not byte strings.) * Remove unnecessary key param from DeleterFn. This is good for efficiency in HyperClockCache, which does not directly store the cache key in memory. (Alternative to https://github.com/facebook/rocksdb/issues/10774) * Add allocator to Cache DeleterFn. This is a kind of future-proofing change in case we get more serious about using the Cache allocator for memory tracked by the Cache. Right now, only the uncompressed block contents are allocated using the allocator, and a pointer to that allocator is saved as part of the cached object so that the deleter can use it. (See CacheAllocationPtr.) If in the future we are able to "flatten out" our Cache objects some more, it would be good not to have to track the allocator as part of each object. * Removes legacy `ApplyToAllCacheEntries` and changes `ApplyToAllEntries` signature for Deleter->CacheItemHelper change. ## typed_cache.h Adds various "typed" interfaces to the Cache as internal APIs, so that most uses of Cache can use simple type safe code without casting and without explicit deleters, etc. Almost all of the non-test, non-glue code uses of Cache have been migrated. (Follow-up work: CompressedSecondaryCache deserves deeper attention to migrate.) This change expands RocksDB's internal usage of metaprogramming and SFINAE (https://en.cppreference.com/w/cpp/language/sfinae). The existing usages of Cache are divided up at a high level into these new interfaces. See updated existing uses of Cache for examples of how these are used. * PlaceholderCacheInterface - Used for making cache reservations, with entries that have a charge but no value. * BasicTypedCacheInterface<TValue> - Used for primary cache storage of objects of type TValue, which can be cleaned up with std::default_delete<TValue>. The role is provided by TValue::kCacheEntryRole or given in an optional template parameter. * FullTypedCacheInterface<TValue, TCreateContext> - Used for secondary cache compatible storage of objects of type TValue. In addition to BasicTypedCacheInterface constraints, we require TValue::ContentSlice() to return persistable data. This simplifies usage for the normal case of simple secondary cache compatibility (can give you a Slice to the data already in memory). In addition to TCreateContext performing the role of Cache::CreateContext, it is also expected to provide a factory function for creating TValue. * For each of these, there's a "Shared" version (e.g. FullTypedSharedCacheInterface) that holds a shared_ptr to the Cache, rather than assuming external ownership by holding only a raw `Cache*`. These interfaces introduce specific handle types for each interface instantiation, so that it's easy to see what kind of object is controlled by a handle. (Ultimately, this might not be worth the extra complexity, but it seems OK so far.) Note: I attempted to make the cache 'charge' automatically inferred from the cache object type, such as by expecting an ApproximateMemoryUsage() function, but this is not so clean because there are cases where we need to compute the charge ahead of time and don't want to re-compute it. ## block_cache.h This header is essentially the replacement for the old block_like_traits.h. It includes various things to support block cache access with typed_cache.h for block-based table. ## block_based_table_reader.cc Before this change, accessing the block cache here was an awkward mix of static polymorphism (template TBlocklike) and switch-case on a dynamic BlockType value. This change mostly unifies on static polymorphism, relying on minor hacks in block_cache.h to distinguish variants of Block. We still check BlockType in some places (especially for stats, which could be improved in follow-up work) but at least the BlockType is a static constant from the template parameter. (No more awkward partial redundancy between static and dynamic info.) This likely contributes to the overall performance improvement, but hasn't been tested in isolation. The other key source of simplification here is a more unified system of creating block cache objects: for directly populating from primary cache and for promotion from secondary cache. Both use BlockCreateContext, for context and for factory functions. ## block_based_table_builder.cc, cache_dump_load_impl.cc Before this change, warming caches was super ugly code. Both of these source files had switch statements to basically transition from the dynamic BlockType world to the static TBlocklike world. None of that mess is needed anymore as there's a new, untyped WarmInCache function that handles all the details just as promotion from SecondaryCache would. (Fixes `TODO akanksha: Dedup below code` in block_based_table_builder.cc.) ## Everything else Mostly just updating Cache users to use new typed APIs when reasonably possible, or changed Cache APIs when not. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10975 Test Plan: tests updated Performance test setup similar to https://github.com/facebook/rocksdb/issues/10626 (by cache size, LRUCache when not "hyper" for HyperClockCache): 34MB 1thread base.hyper -> kops/s: 0.745 io_bytes/op: 2.52504e+06 miss_ratio: 0.140906 max_rss_mb: 76.4844 34MB 1thread new.hyper -> kops/s: 0.751 io_bytes/op: 2.5123e+06 miss_ratio: 0.140161 max_rss_mb: 79.3594 34MB 1thread base -> kops/s: 0.254 io_bytes/op: 1.36073e+07 miss_ratio: 0.918818 max_rss_mb: 45.9297 34MB 1thread new -> kops/s: 0.252 io_bytes/op: 1.36157e+07 miss_ratio: 0.918999 max_rss_mb: 44.1523 34MB 32thread base.hyper -> kops/s: 7.272 io_bytes/op: 2.88323e+06 miss_ratio: 0.162532 max_rss_mb: 516.602 34MB 32thread new.hyper -> kops/s: 7.214 io_bytes/op: 2.99046e+06 miss_ratio: 0.168818 max_rss_mb: 518.293 34MB 32thread base -> kops/s: 3.528 io_bytes/op: 1.35722e+07 miss_ratio: 0.914691 max_rss_mb: 264.926 34MB 32thread new -> kops/s: 3.604 io_bytes/op: 1.35744e+07 miss_ratio: 0.915054 max_rss_mb: 264.488 233MB 1thread base.hyper -> kops/s: 53.909 io_bytes/op: 2552.35 miss_ratio: 0.0440566 max_rss_mb: 241.984 233MB 1thread new.hyper -> kops/s: 62.792 io_bytes/op: 2549.79 miss_ratio: 0.044043 max_rss_mb: 241.922 233MB 1thread base -> kops/s: 1.197 io_bytes/op: 2.75173e+06 miss_ratio: 0.103093 max_rss_mb: 241.559 233MB 1thread new -> kops/s: 1.199 io_bytes/op: 2.73723e+06 miss_ratio: 0.10305 max_rss_mb: 240.93 233MB 32thread base.hyper -> kops/s: 1298.69 io_bytes/op: 2539.12 miss_ratio: 0.0440307 max_rss_mb: 371.418 233MB 32thread new.hyper -> kops/s: 1421.35 io_bytes/op: 2538.75 miss_ratio: 0.0440307 max_rss_mb: 347.273 233MB 32thread base -> kops/s: 9.693 io_bytes/op: 2.77304e+06 miss_ratio: 0.103745 max_rss_mb: 569.691 233MB 32thread new -> kops/s: 9.75 io_bytes/op: 2.77559e+06 miss_ratio: 0.103798 max_rss_mb: 552.82 1597MB 1thread base.hyper -> kops/s: 58.607 io_bytes/op: 1449.14 miss_ratio: 0.0249324 max_rss_mb: 1583.55 1597MB 1thread new.hyper -> kops/s: 69.6 io_bytes/op: 1434.89 miss_ratio: 0.0247167 max_rss_mb: 1584.02 1597MB 1thread base -> kops/s: 60.478 io_bytes/op: 1421.28 miss_ratio: 0.024452 max_rss_mb: 1589.45 1597MB 1thread new -> kops/s: 63.973 io_bytes/op: 1416.07 miss_ratio: 0.0243766 max_rss_mb: 1589.24 1597MB 32thread base.hyper -> kops/s: 1436.2 io_bytes/op: 1357.93 miss_ratio: 0.0235353 max_rss_mb: 1692.92 1597MB 32thread new.hyper -> kops/s: 1605.03 io_bytes/op: 1358.04 miss_ratio: 0.023538 max_rss_mb: 1702.78 1597MB 32thread base -> kops/s: 280.059 io_bytes/op: 1350.34 miss_ratio: 0.023289 max_rss_mb: 1675.36 1597MB 32thread new -> kops/s: 283.125 io_bytes/op: 1351.05 miss_ratio: 0.0232797 max_rss_mb: 1703.83 Almost uniformly improving over base revision, especially for hot paths with HyperClockCache, up to 12% higher throughput seen (1597MB, 32thread, hyper). The improvement for that is likely coming from much simplified code for providing context for secondary cache promotion (CreateCallback/CreateContext), and possibly from less branching in block_based_table_reader. And likely a small improvement from not reconstituting key for DeleterFn. Reviewed By: anand1976 Differential Revision: D42417818 Pulled By: pdillinger fbshipit-source-id: f86bfdd584dce27c028b151ba56818ad14f7a432
2 years ago
sec_cache->GetHelper(true)->del_cb(chunks_head, /*alloc*/ nullptr);
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
}
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
};
class CompressedSecCacheTestWithCompressAndAllocatorParam
: public CompressedSecondaryCacheTest,
public ::testing::WithParamInterface<std::tuple<bool, bool>> {
public:
CompressedSecCacheTestWithCompressAndAllocatorParam() {
sec_cache_is_compressed_ = std::get<0>(GetParam());
use_jemalloc_ = std::get<1>(GetParam());
}
bool sec_cache_is_compressed_;
bool use_jemalloc_;
};
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TEST_P(CompressedSecCacheTestWithCompressAndAllocatorParam, BasicTes) {
BasicTest(sec_cache_is_compressed_, use_jemalloc_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
INSTANTIATE_TEST_CASE_P(CompressedSecCacheTests,
CompressedSecCacheTestWithCompressAndAllocatorParam,
::testing::Combine(testing::Bool(), testing::Bool()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
class CompressedSecondaryCacheTestWithCompressionParam
: public CompressedSecondaryCacheTest,
public ::testing::WithParamInterface<bool> {
public:
CompressedSecondaryCacheTestWithCompressionParam() {
sec_cache_is_compressed_ = GetParam();
}
bool sec_cache_is_compressed_;
};
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TEST_P(CompressedSecondaryCacheTestWithCompressionParam, BasicTestFromString) {
std::shared_ptr<SecondaryCache> sec_cache{nullptr};
std::string sec_cache_uri;
if (sec_cache_is_compressed_) {
if (LZ4_Supported()) {
sec_cache_uri =
"compressed_secondary_cache://"
"capacity=2048;num_shard_bits=0;compression_type=kLZ4Compression;"
"compress_format_version=2";
} else {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
sec_cache_uri =
"compressed_secondary_cache://"
"capacity=2048;num_shard_bits=0;compression_type=kNoCompression";
sec_cache_is_compressed_ = false;
}
Status s = SecondaryCache::CreateFromString(ConfigOptions(), sec_cache_uri,
&sec_cache);
EXPECT_OK(s);
} else {
sec_cache_uri =
"compressed_secondary_cache://"
"capacity=2048;num_shard_bits=0;compression_type=kNoCompression";
Status s = SecondaryCache::CreateFromString(ConfigOptions(), sec_cache_uri,
&sec_cache);
EXPECT_OK(s);
}
BasicTestHelper(sec_cache, sec_cache_is_compressed_);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
}
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TEST_P(CompressedSecondaryCacheTestWithCompressionParam,
BasicTestFromStringWithSplit) {
std::shared_ptr<SecondaryCache> sec_cache{nullptr};
std::string sec_cache_uri;
if (sec_cache_is_compressed_) {
if (LZ4_Supported()) {
sec_cache_uri =
"compressed_secondary_cache://"
"capacity=2048;num_shard_bits=0;compression_type=kLZ4Compression;"
"compress_format_version=2;enable_custom_split_merge=true";
} else {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
sec_cache_uri =
"compressed_secondary_cache://"
"capacity=2048;num_shard_bits=0;compression_type=kNoCompression;"
"enable_custom_split_merge=true";
sec_cache_is_compressed_ = false;
}
Status s = SecondaryCache::CreateFromString(ConfigOptions(), sec_cache_uri,
&sec_cache);
EXPECT_OK(s);
} else {
sec_cache_uri =
"compressed_secondary_cache://"
"capacity=2048;num_shard_bits=0;compression_type=kNoCompression;"
"enable_custom_split_merge=true";
Status s = SecondaryCache::CreateFromString(ConfigOptions(), sec_cache_uri,
&sec_cache);
EXPECT_OK(s);
}
BasicTestHelper(sec_cache, sec_cache_is_compressed_);
Prevent double caching in the compressed secondary cache (#9747) Summary: ### **Summary:** When both LRU Cache and CompressedSecondaryCache are configured together, there possibly are some data blocks double cached. **Changes include:** 1. Update IS_PROMOTED to IS_IN_SECONDARY_CACHE to prevent confusions. 2. This PR updates SecondaryCacheResultHandle and use IsErasedFromSecondaryCache to determine whether the handle is erased in the secondary cache. Then, the caller can determine whether to SetIsInSecondaryCache(). 3. Rename LRUSecondaryCache to CompressedSecondaryCache. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9747 Test Plan: **Test Scripts:** 1. Populate a DB. The on disk footprint is 482 MB. The data is set to be 50% compressible, so the total decompressed size is expected to be 964 MB. ./db_bench --benchmarks=fillrandom --num=10000000 -db=/db_bench_1 2. overwrite it to a stable state: ./db_bench --benchmarks=overwrite,stats --num=10000000 -use_existing_db -duration=10 --benchmark_write_rate_limit=2000000 -db=/db_bench_1 4. Run read tests with diffeernt cache setting: T1: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 --statistics -db=/db_bench_1 T2: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=320000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T3: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=520000000 -compressed_secondary_cache_size=400000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 T4: ./db_bench --benchmarks=seekrandom,stats --threads=16 --num=10000000 -use_existing_db -duration=120 --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=20000000 -compressed_secondary_cache_size=500000000 --statistics -use_compressed_secondary_cache -db=/db_bench_1 **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 96.2% | |520 MB | 400 MB | 98.3% | |20 MB | 500 MB | 98.8% | **Before this PR** | Cache Size | Compressed Secondary Cache Size | Cache Hit Rate | |------------|-------------------------------------|----------------| |520 MB | 0 MB | 85.5% | |320 MB | 400 MB | 99.9% | |520 MB | 400 MB | 99.9% | |20 MB | 500 MB | 99.2% | Reviewed By: anand1976 Differential Revision: D35117499 Pulled By: gitbw95 fbshipit-source-id: ea2657749fc13efebe91a8a1b56bc61d6a224a12
3 years ago
}
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TEST_P(CompressedSecondaryCacheTestWithCompressionParam, FailsTest) {
FailsTest(sec_cache_is_compressed_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
TEST_P(CompressedSecondaryCacheTestWithCompressionParam,
BasicIntegrationFailTest) {
BasicIntegrationFailTest(sec_cache_is_compressed_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
TEST_P(CompressedSecondaryCacheTestWithCompressionParam,
IntegrationSaveFailTest) {
IntegrationSaveFailTest(sec_cache_is_compressed_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
TEST_P(CompressedSecondaryCacheTestWithCompressionParam,
IntegrationCreateFailTest) {
IntegrationCreateFailTest(sec_cache_is_compressed_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
TEST_P(CompressedSecondaryCacheTestWithCompressionParam,
IntegrationFullCapacityTest) {
IntegrationFullCapacityTest(sec_cache_is_compressed_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
TEST_P(CompressedSecondaryCacheTestWithCompressionParam, EntryRoles) {
CompressedSecondaryCacheOptions opts;
opts.capacity = 2048;
opts.num_shard_bits = 0;
if (sec_cache_is_compressed_) {
if (!LZ4_Supported()) {
ROCKSDB_GTEST_SKIP("This test requires LZ4 support.");
return;
}
} else {
opts.compression_type = CompressionType::kNoCompression;
}
// Select a random subset to include, for fast test
Random& r = *Random::GetTLSInstance();
CacheEntryRoleSet do_not_compress;
for (uint32_t i = 0; i < kNumCacheEntryRoles; ++i) {
// A few included on average, but decent chance of zero
if (r.OneIn(5)) {
do_not_compress.Add(static_cast<CacheEntryRole>(i));
}
}
opts.do_not_compress_roles = do_not_compress;
std::shared_ptr<SecondaryCache> sec_cache = NewCompressedSecondaryCache(opts);
// Fixed seed to ensure consistent compressibility (doesn't compress)
std::string junk(Random(301).RandomString(1000));
for (uint32_t i = 0; i < kNumCacheEntryRoles; ++i) {
CacheEntryRole role = static_cast<CacheEntryRole>(i);
// Uniquify `junk`
junk[0] = static_cast<char>(i);
TestItem item{junk.data(), junk.length()};
Slice ith_key = Slice(junk.data(), 5);
get_perf_context()->Reset();
ASSERT_OK(sec_cache->Insert(ith_key, &item, GetHelper(role)));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_dummy_count, 1U);
ASSERT_OK(sec_cache->Insert(ith_key, &item, GetHelper(role)));
ASSERT_EQ(get_perf_context()->compressed_sec_cache_insert_real_count, 1U);
bool kept_in_sec_cache{true};
std::unique_ptr<SecondaryCacheResultHandle> handle =
sec_cache->Lookup(ith_key, GetHelper(role), this, true,
/*advise_erase=*/true, kept_in_sec_cache);
ASSERT_NE(handle, nullptr);
// Lookup returns the right data
std::unique_ptr<TestItem> val =
std::unique_ptr<TestItem>(static_cast<TestItem*>(handle->Value()));
ASSERT_NE(val, nullptr);
ASSERT_EQ(memcmp(val->Buf(), item.Buf(), item.Size()), 0);
bool compressed =
sec_cache_is_compressed_ && !do_not_compress.Contains(role);
if (compressed) {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes,
1000);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes,
1007);
} else {
ASSERT_EQ(get_perf_context()->compressed_sec_cache_uncompressed_bytes, 0);
ASSERT_EQ(get_perf_context()->compressed_sec_cache_compressed_bytes, 0);
}
}
}
INSTANTIATE_TEST_CASE_P(CompressedSecCacheTests,
CompressedSecondaryCacheTestWithCompressionParam,
testing::Bool());
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
class CompressedSecCacheTestWithCompressAndSplitParam
: public CompressedSecondaryCacheTest,
public ::testing::WithParamInterface<std::tuple<bool, bool>> {
public:
CompressedSecCacheTestWithCompressAndSplitParam() {
sec_cache_is_compressed_ = std::get<0>(GetParam());
enable_custom_split_merge_ = std::get<1>(GetParam());
}
bool sec_cache_is_compressed_;
bool enable_custom_split_merge_;
};
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
TEST_P(CompressedSecCacheTestWithCompressAndSplitParam, BasicIntegrationTest) {
BasicIntegrationTest(sec_cache_is_compressed_, enable_custom_split_merge_);
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
}
INSTANTIATE_TEST_CASE_P(CompressedSecCacheTests,
CompressedSecCacheTestWithCompressAndSplitParam,
::testing::Combine(testing::Bool(), testing::Bool()));
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
Split cache to minimize internal fragmentation (#10287) Summary: ### **Summary:** To minimize the internal fragmentation caused by the variable size of the compressed blocks, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`. Based on the analysis of the results of the following tests, from the overall internal fragmentation perspective, this PR does mitigate the internal fragmentation issue. _Do more myshadow tests with the latest commit. I finished several myshadow AB Testing and the results are promising. For the config of 4GB primary cache and 3GB secondary cache, Jemalloc resident stats shows consistently ~0.15GB memory saving; the allocated and active stats show similar memory savings. The CPU usage is almost the same before and after this PR._ To evaluate the issue of memory fragmentations and the benefits of this PR, I conducted two sets of local tests as follows. **T1** Keys: 16 bytes each (+ 0 bytes user-defined timestamp) Values: 100 bytes each (50 bytes after compression) Entries: 90000000 RawSize: 9956.4 MB (estimated) FileSize: 5664.8 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T1_3 | 4000 | 4000 | | T1_4 | 2000 | 3000 | Populate the DB: ./db_bench --benchmarks=fillrandom --num=90000000 -db=/mem_fragmentation/db_bench_1 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=90000000 -use_existing_db -db=/mem_fragmentation/db_bench_1 Run read tests with differnt cache setting: T1_3: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_3_20220710 -duration=1800 & T1_4: MALLOC_CONF="prof:true,prof_stats:true" ../rocksdb/db_bench --benchmarks=seekrandom --threads=16 --num=90000000 -use_existing_db --benchmark_write_rate_limit=52000000 -use_direct_reads --cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -db=/mem_fragmentation/db_bench_1 --print_malloc_stats=true > ~/temp/mem_frag/20220710/jemalloc_stats_json_T1_4_20220710 -duration=1800 & For T1_3 and T1_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T1_3 | T1_3 after mem defrag | T1_4 | T1_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8728 | 8076 | 5518 | 5043 | | available (MB) | 8753 | 8092 | 5536 | 5051 | | external fragmentation rate | 0.003 | 0.002 | 0.003 | 0.0016 | | resident (MB) | 8956 | 8365 | 5655 | 5235 | **T2** Keys: 32 bytes each (+ 0 bytes user-defined timestamp) Values: 256 bytes each (128 bytes after compression) Entries: 40000000 RawSize: 10986.3 MB (estimated) FileSize: 6103.5 MB (estimated) | Test Name | Primary Cache Size (MB) | Compressed Secondary Cache Size (MB) | | - | - | - | | T2_3 | 4000 | 4000 | | T2_4 | 2000 | 3000 | Create DB (10GB): ./db_bench -benchmarks=fillrandom -use_direct_reads=true -num=40000000 -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Overwrite it to a stable state: ./db_bench --benchmarks=overwrite --num=40000000 -use_existing_db -key_size=32 -value_size=256 -db=/mem_fragmentation/db_bench_2 Run read tests with differnt cache setting: T2_3: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=4000000000 -compressed_secondary_cache_size=4000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_3 -duration=1800 & T2_4: MALLOC_CONF="prof:true,prof_stats:true" ./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=2000000000 -compressed_secondary_cache_size=3000000000 -use_compressed_secondary_cache -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=1000 -sine_b=0.000073 -sine_d=400000 -reads=80000000 -num=40000000 -key_size=32 -value_size=256 -use_existing_db=true -db=/mem_fragmentation/db_bench_2 --print_malloc_stats=true > ~/temp/mem_frag/jemalloc_stats_T2_4 -duration=1800 & For T2_3 and T2_4, I also conducted the tests before and after this PR. The following table show the important jemalloc stats. | Test Name | T2_3 | T2_3 after mem defrag | T2_4 | T2_4 after mem defrag | | - | - | - | - | - | | allocated (MB) | 8425 | 8093 | 5426 | 5149 | | available (MB) | 8489 | 8138 | 5435 | 5158 | | external fragmentation rate | 0.008 | 0.0055 | 0.0017 | 0.0017 | | resident (MB) | 8676 | 8392 | 5541 | 5321 | Pull Request resolved: https://github.com/facebook/rocksdb/pull/10287 Test Plan: Unit tests. Reviewed By: anand1976 Differential Revision: D37743362 Pulled By: gitbw95 fbshipit-source-id: 0010c5af08addeacc5ebbc4ffe5be882fb1d38ad
2 years ago
TEST_F(CompressedSecondaryCacheTest, SplitValueIntoChunksTest) {
SplitValueIntoChunksTest();
}
TEST_F(CompressedSecondaryCacheTest, MergeChunksIntoValueTest) {
MergeChunksIntoValueTest();
}
TEST_F(CompressedSecondaryCacheTest, SplictValueAndMergeChunksTest) {
SplictValueAndMergeChunksTest();
}
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
Add a secondary cache implementation based on LRUCache 1 (#9518) Summary: **Summary:** RocksDB uses a block cache to reduce IO and make queries more efficient. The block cache is based on the LRU algorithm (LRUCache) and keeps objects containing uncompressed data, such as Block, ParsedFullFilterBlock etc. It allows the user to configure a second level cache (rocksdb::SecondaryCache) to extend the primary block cache by holding items evicted from it. Some of the major RocksDB users, like MyRocks, use direct IO and would like to use a primary block cache for uncompressed data and a secondary cache for compressed data. The latter allows us to mitigate the loss of the Linux page cache due to direct IO. This PR includes a concrete implementation of rocksdb::SecondaryCache that integrates with compression libraries such as LZ4 and implements an LRU cache to hold compressed blocks. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9518 Test Plan: In this PR, the lru_secondary_cache_test.cc includes the following tests: 1. The unit tests for the secondary cache with either compression or no compression, such as basic tests, fails tests. 2. The integration tests with both primary cache and this secondary cache . **Follow Up:** 1. Statistics (e.g. compression ratio) will be added in another PR. 2. Once this implementation is ready, I will do some shadow testing and benchmarking with UDB to measure the impact. Reviewed By: anand1976 Differential Revision: D34430930 Pulled By: gitbw95 fbshipit-source-id: 218d78b672a2f914856d8a90ff32f2f5b5043ded
3 years ago
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}