Summary: AFIK, options builder is not used by anyone. Remove it. Test Plan: Run all existing tests. Reviewers: IslamAbdelRahman, andrewkr, igor Reviewed By: igor Subscribers: leveldb, andrewkr, dhruba Differential Revision: https://reviews.facebook.net/D59319main
sdong
9 years ago
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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#include <math.h> |
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#include <cmath> |
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#include <algorithm> |
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#include "rocksdb/options.h" |
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namespace rocksdb { |
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namespace { |
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// For now, always use 1-0 as level bytes multiplier.
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const int kBytesForLevelMultiplier = 10; |
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const size_t kBytesForOneMb = 1024 * 1024; |
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// Pick compaction style
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CompactionStyle PickCompactionStyle(size_t write_buffer_size, |
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int read_amp_threshold, |
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int write_amp_threshold, |
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uint64_t target_db_size) { |
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#ifndef ROCKSDB_LITE |
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// Estimate read amplification and write amplification of two compaction
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// styles. If there is hard limit to force a choice, make the choice.
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// Otherwise, calculate a score based on threshold and expected value of
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// two styles, weighing reads 4X important than writes.
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int expected_levels = static_cast<int>(ceil( |
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std::log(target_db_size / write_buffer_size) / std::log(kBytesForLevelMultiplier))); |
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int expected_max_files_universal = |
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static_cast<int>(ceil(log2(target_db_size / write_buffer_size))); |
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const int kEstimatedLevel0FilesInLevelStyle = 2; |
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// Estimate write amplification:
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// (1) 1 for every L0 file
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// (2) 2 for L1
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// (3) kBytesForLevelMultiplier for the last level. It's really hard to
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// predict.
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// (3) kBytesForLevelMultiplier for other levels.
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int expected_write_amp_level = kEstimatedLevel0FilesInLevelStyle + 2 |
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+ (expected_levels - 2) * kBytesForLevelMultiplier |
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+ kBytesForLevelMultiplier; |
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int expected_read_amp_level = |
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kEstimatedLevel0FilesInLevelStyle + expected_levels; |
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int max_read_amp_uni = expected_max_files_universal; |
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if (read_amp_threshold <= max_read_amp_uni) { |
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return kCompactionStyleLevel; |
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} else if (write_amp_threshold <= expected_write_amp_level) { |
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return kCompactionStyleUniversal; |
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} |
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const double kReadWriteWeight = 4; |
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double level_ratio = |
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static_cast<double>(read_amp_threshold) / expected_read_amp_level * |
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kReadWriteWeight + |
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static_cast<double>(write_amp_threshold) / expected_write_amp_level; |
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int expected_write_amp_uni = expected_max_files_universal / 2 + 2; |
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int expected_read_amp_uni = expected_max_files_universal / 2 + 1; |
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double uni_ratio = |
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static_cast<double>(read_amp_threshold) / expected_read_amp_uni * |
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kReadWriteWeight + |
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static_cast<double>(write_amp_threshold) / expected_write_amp_uni; |
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if (level_ratio > uni_ratio) { |
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return kCompactionStyleLevel; |
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} else { |
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return kCompactionStyleUniversal; |
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} |
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#else |
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return kCompactionStyleLevel; |
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#endif // !ROCKSDB_LITE
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} |
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// Pick mem table size
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void PickWriteBufferSize(size_t total_write_buffer_limit, Options* options) { |
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const size_t kMaxWriteBufferSize = 128 * kBytesForOneMb; |
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const size_t kMinWriteBufferSize = 4 * kBytesForOneMb; |
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// Try to pick up a buffer size between 4MB and 128MB.
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// And try to pick 4 as the total number of write buffers.
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size_t write_buffer_size = total_write_buffer_limit / 4; |
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if (write_buffer_size > kMaxWriteBufferSize) { |
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write_buffer_size = kMaxWriteBufferSize; |
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} else if (write_buffer_size < kMinWriteBufferSize) { |
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write_buffer_size = std::min(static_cast<size_t>(kMinWriteBufferSize), |
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total_write_buffer_limit / 2); |
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} |
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// Truncate to multiple of 1MB.
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if (write_buffer_size % kBytesForOneMb != 0) { |
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write_buffer_size = |
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(write_buffer_size / kBytesForOneMb + 1) * kBytesForOneMb; |
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} |
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options->write_buffer_size = write_buffer_size; |
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options->max_write_buffer_number = |
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static_cast<int>(total_write_buffer_limit / write_buffer_size); |
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options->min_write_buffer_number_to_merge = 1; |
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} |
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#ifndef ROCKSDB_LITE |
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void OptimizeForUniversal(Options* options) { |
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options->level0_file_num_compaction_trigger = 2; |
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options->level0_slowdown_writes_trigger = 30; |
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options->level0_stop_writes_trigger = 40; |
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options->max_open_files = -1; |
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} |
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#endif |
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// Optimize parameters for level-based compaction
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void OptimizeForLevel(int read_amplification_threshold, |
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int write_amplification_threshold, |
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uint64_t target_db_size, Options* options) { |
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int expected_levels_one_level0_file = |
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static_cast<int>(ceil(std::log(target_db_size / options->write_buffer_size) / |
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std::log(kBytesForLevelMultiplier))); |
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int level0_stop_writes_trigger = |
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read_amplification_threshold - expected_levels_one_level0_file; |
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const size_t kInitialLevel0TotalSize = 128 * kBytesForOneMb; |
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const int kMaxFileNumCompactionTrigger = 4; |
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const int kMinLevel0StopTrigger = 3; |
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int file_num_buffer = static_cast<int>( |
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kInitialLevel0TotalSize / options->write_buffer_size + 1); |
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if (level0_stop_writes_trigger > file_num_buffer) { |
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// Have sufficient room for multiple level 0 files
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// Try enlarge the buffer up to 1GB
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// Try to enlarge the buffer up to 1GB, if still have sufficient headroom.
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file_num_buffer *= |
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1 << std::max(0, std::min(3, level0_stop_writes_trigger - |
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file_num_buffer - 2)); |
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options->level0_stop_writes_trigger = level0_stop_writes_trigger; |
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options->level0_slowdown_writes_trigger = level0_stop_writes_trigger - 2; |
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options->level0_file_num_compaction_trigger = |
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std::min(kMaxFileNumCompactionTrigger, file_num_buffer / 2); |
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} else { |
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options->level0_stop_writes_trigger = |
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std::max(kMinLevel0StopTrigger, file_num_buffer); |
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options->level0_slowdown_writes_trigger = |
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options->level0_stop_writes_trigger - 1; |
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options->level0_file_num_compaction_trigger = 1; |
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} |
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// This doesn't consider compaction and overheads of mem tables. But usually
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// it is in the same order of magnitude.
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size_t expected_level0_compaction_size = |
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options->level0_file_num_compaction_trigger * options->write_buffer_size; |
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// Enlarge level1 target file size if level0 compaction size is larger.
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uint64_t max_bytes_for_level_base = 10 * kBytesForOneMb; |
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if (expected_level0_compaction_size > max_bytes_for_level_base) { |
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max_bytes_for_level_base = expected_level0_compaction_size; |
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} |
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options->max_bytes_for_level_base = max_bytes_for_level_base; |
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// Now always set level multiplier to be 10
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options->max_bytes_for_level_multiplier = kBytesForLevelMultiplier; |
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const uint64_t kMinFileSize = 2 * kBytesForOneMb; |
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// Allow at least 3-way parallelism for compaction between level 1 and 2.
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uint64_t max_file_size = max_bytes_for_level_base / 3; |
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if (max_file_size < kMinFileSize) { |
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options->target_file_size_base = kMinFileSize; |
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} else { |
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if (max_file_size % kBytesForOneMb != 0) { |
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max_file_size = (max_file_size / kBytesForOneMb + 1) * kBytesForOneMb; |
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} |
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options->target_file_size_base = max_file_size; |
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} |
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// TODO: consider to tune num_levels too.
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} |
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} // namespace
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Options GetOptions(size_t total_write_buffer_limit, |
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int read_amplification_threshold, |
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int write_amplification_threshold, uint64_t target_db_size) { |
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Options options; |
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PickWriteBufferSize(total_write_buffer_limit, &options); |
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size_t write_buffer_size = options.write_buffer_size; |
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options.compaction_style = |
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PickCompactionStyle(write_buffer_size, read_amplification_threshold, |
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write_amplification_threshold, target_db_size); |
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#ifndef ROCKSDB_LITE |
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if (options.compaction_style == kCompactionStyleUniversal) { |
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OptimizeForUniversal(&options); |
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} else { |
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#else |
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{ |
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#endif // !ROCKSDB_LITE
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OptimizeForLevel(read_amplification_threshold, |
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write_amplification_threshold, target_db_size, &options); |
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} |
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return options; |
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} |
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} // namespace rocksdb
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