4 Commits (ca7ccbe2ea6be042f90f31eb75ad4dca032dbed1)

Author	SHA1	Message	Date
Peter Dillinger	2837008525	Vary key size and alignment in filter_bench (#5933) ... Summary: The first version of filter_bench has selectable key size but that size does not vary throughout a test run. This artificially favors "branchy" hash functions like the existing BloomHash, MurmurHash1, probably because of optimal return for branch prediction. This change primarily varies those key sizes from -2 to +2 bytes vs. the average selected size. We also set the default key size at 24 to better reflect our best guess of typical key size. But steadily random key sizes may not be realistic either. So this change introduces a new filter_bench option: -vary_key_size_log2_interval=n where the same key size is used 2^n times and then changes to another size. I've set the default at 5 (32 times same size) as a compromise between deployments with rather consistent vs. rather variable key sizes. On my Skylake system, the performance boost to MurmurHash1 largely lies between n=10 and n=15. Also added -vary_key_alignment (bool, now default=true), though this doesn't currently seem to matter in hash functions under consideration. This change also does a "dry run" for each testing scenario, to improve the accuracy of those numbers, as there was more difference between scenarios than expected. Subtracting gross test run times from dry run times is now also embedded in the output, because these "net" times are generally the most useful. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5933 Differential Revision: D18121683 Pulled By: pdillinger fbshipit-source-id: 3c7efee1c5661a5fe43de555e786754ddf80dc1e	6 years ago
Levi Tamasi	29ccf2075c	Store the filter bits reader alongside the filter block contents (#5936) ... Summary: Amongst other things, PR https://github.com/facebook/rocksdb/issues/5504 refactored the filter block readers so that only the filter block contents are stored in the block cache (as opposed to the earlier design where the cache stored the filter block reader itself, leading to potentially dangling pointers and concurrency bugs). However, this change introduced a performance hit since with the new code, the metadata fields are re-parsed upon every access. This patch reunites the block contents with the filter bits reader to eliminate this overhead; since this is still a self-contained pure data object, it is safe to store it in the cache. (Note: this is similar to how the zstd digest is handled.) Pull Request resolved: https://github.com/facebook/rocksdb/pull/5936 Test Plan: make asan_check filter_bench results for the old code: ``` $ ./filter_bench -quick WARNING: Assertions are enabled; benchmarks unnecessarily slow Building... Build avg ns/key: 26.7153 Number of filters: 16669 Total memory (MB): 200.009 Bits/key actual: 10.0647 ---------------------------- Inside queries... Dry run (46b) ns/op: 33.4258 Single filter ns/op: 42.5974 Random filter ns/op: 217.861 ---------------------------- Outside queries... Dry run (25d) ns/op: 32.4217 Single filter ns/op: 50.9855 Random filter ns/op: 219.167 Average FP rate %: 1.13993 ---------------------------- Done. (For more info, run with -legend or -help.) $ ./filter_bench -quick -use_full_block_reader WARNING: Assertions are enabled; benchmarks unnecessarily slow Building... Build avg ns/key: 26.5172 Number of filters: 16669 Total memory (MB): 200.009 Bits/key actual: 10.0647 ---------------------------- Inside queries... Dry run (46b) ns/op: 32.3556 Single filter ns/op: 83.2239 Random filter ns/op: 370.676 ---------------------------- Outside queries... Dry run (25d) ns/op: 32.2265 Single filter ns/op: 93.5651 Random filter ns/op: 408.393 Average FP rate %: 1.13993 ---------------------------- Done. (For more info, run with -legend or -help.) ``` With the new code: ``` $ ./filter_bench -quick WARNING: Assertions are enabled; benchmarks unnecessarily slow Building... Build avg ns/key: 25.4285 Number of filters: 16669 Total memory (MB): 200.009 Bits/key actual: 10.0647 ---------------------------- Inside queries... Dry run (46b) ns/op: 31.0594 Single filter ns/op: 43.8974 Random filter ns/op: 226.075 ---------------------------- Outside queries... Dry run (25d) ns/op: 31.0295 Single filter ns/op: 50.3824 Random filter ns/op: 226.805 Average FP rate %: 1.13993 ---------------------------- Done. (For more info, run with -legend or -help.) $ ./filter_bench -quick -use_full_block_reader WARNING: Assertions are enabled; benchmarks unnecessarily slow Building... Build avg ns/key: 26.5308 Number of filters: 16669 Total memory (MB): 200.009 Bits/key actual: 10.0647 ---------------------------- Inside queries... Dry run (46b) ns/op: 33.2968 Single filter ns/op: 58.6163 Random filter ns/op: 291.434 ---------------------------- Outside queries... Dry run (25d) ns/op: 32.1839 Single filter ns/op: 66.9039 Random filter ns/op: 292.828 Average FP rate %: 1.13993 ---------------------------- Done. (For more info, run with -legend or -help.) ``` Differential Revision: D17991712 Pulled By: ltamasi fbshipit-source-id: 7ea205550217bfaaa1d5158ebd658e5832e60f29	6 years ago
Peter Dillinger	90e285efde	Fix some implicit conversions in filter_bench (#5894) ... Summary: Fixed some spots where converting size_t or uint_fast32_t to uint32_t. Wrapped mt19937 in a new Random32 class to avoid future such traps. NB: I tried using Random32::Uniform (std::uniform_int_distribution) in filter_bench instead of fastrange, but that more than doubled the dry run time! So I added fastrange as Random32::Uniformish. ;) Pull Request resolved: https://github.com/facebook/rocksdb/pull/5894 Test Plan: USE_CLANG=1 build, and manual re-run filter_bench Differential Revision: D17825131 Pulled By: pdillinger fbshipit-source-id: 68feee333b5f8193c084ded760e3d6679b405ecd	6 years ago
Peter Dillinger	46ca51d430	filter_bench - a prelim tool for SST filter benchmarking (#5825) ... Summary: Example: using the tool before and after PR https://github.com/facebook/rocksdb/issues/5784 shows that the refactoring, presumed performance-neutral, actually sped up SST filters by about 3% to 8% (repeatable result): Before: - Dry run ns/op: 22.4725 - Single filter ns/op: 51.1078 - Random filter ns/op: 120.133 After: + Dry run ns/op: 22.2301 + Single filter run ns/op: 47.4313 + Random filter ns/op: 115.9 Only tests filters for the block-based table (full filters and partitioned filters - same implementation; not block-based filters), which seems to be the recommended format/implementation. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5825 Differential Revision: D17804987 Pulled By: pdillinger fbshipit-source-id: 0f18a9c254c57f7866030d03e7fa4ba503bac3c5	6 years ago