From c83b085770c003a2e2d30ceb24976aa388347d7f Mon Sep 17 00:00:00 2001 From: Lei Jin Date: Thu, 12 Jun 2014 10:06:18 -0700 Subject: [PATCH] prefetch bloom filter data block for L0 files Summary: as title Test Plan: db_bench the initial result is very promising. I will post results of complete runs Reviewers: dhruba, haobo, sdong, igor Reviewed By: sdong Subscribers: leveldb Differential Revision: https://reviews.facebook.net/D18867 --- db/version_set.cc | 11 +++++++++++ db/version_set.h | 1 + port/port_posix.h | 2 ++ table/plain_table_reader.cc | 7 +++++++ table/plain_table_reader.h | 2 ++ table/table_reader.h | 3 +++ util/dynamic_bloom.h | 15 ++++++++++++--- 7 files changed, 38 insertions(+), 3 deletions(-) diff --git a/db/version_set.cc b/db/version_set.cc index c6a9e6ab1..aee19dd1d 100644 --- a/db/version_set.cc +++ b/db/version_set.cc @@ -567,6 +567,16 @@ void Version::Get(const ReadOptions& options, continue; } + // Prefetch table data to avoid cache miss if possible + if (level == 0) { + for (int i = 0; i < num_files; ++i) { + auto* r = files_[0][i]->table_reader; + if (r) { + r->Prepare(ikey); + } + } + } + // Get the list of files to search in this level FileMetaData* const* files = &files_[level][0]; @@ -607,6 +617,7 @@ void Version::Get(const ReadOptions& options, for (int32_t i = start_index; i < num_files;) { FileMetaData* f = files[i]; + // Check if key is within a file's range. If search left bound and right // bound point to the same find, we are sure key falls in range. assert(level == 0 || i == start_index || diff --git a/db/version_set.h b/db/version_set.h index 7c8d7146e..446dcf133 100644 --- a/db/version_set.h +++ b/db/version_set.h @@ -92,6 +92,7 @@ class Version { FileMetaData* seek_file; int seek_file_level; }; + void Get(const ReadOptions&, const LookupKey& key, std::string* val, Status* status, MergeContext* merge_context, GetStats* stats, bool* value_found = nullptr); diff --git a/port/port_posix.h b/port/port_posix.h index d20a5dff2..f048d54ce 100644 --- a/port/port_posix.h +++ b/port/port_posix.h @@ -482,6 +482,8 @@ inline bool LZ4HC_Compress(const CompressionOptions &opts, const char* input, #define CACHE_LINE_SIZE 64U +#define PREFETCH(addr, rw, locality) __builtin_prefetch(addr, rw, locality) + } // namespace port } // namespace rocksdb diff --git a/table/plain_table_reader.cc b/table/plain_table_reader.cc index 139c30c30..e0da7e8c6 100644 --- a/table/plain_table_reader.cc +++ b/table/plain_table_reader.cc @@ -610,6 +610,13 @@ Status PlainTableReader::Next(uint32_t* offset, ParsedInternalKey* key, return Status::OK(); } +void PlainTableReader::Prepare(const Slice& target) { + if (enable_bloom_) { + uint32_t prefix_hash = GetSliceHash(GetPrefix(target)); + bloom_.Prefetch(prefix_hash); + } +} + Status PlainTableReader::Get(const ReadOptions& ro, const Slice& target, void* arg, bool (*saver)(void*, const ParsedInternalKey&, diff --git a/table/plain_table_reader.h b/table/plain_table_reader.h index e20a109c7..9936847e3 100644 --- a/table/plain_table_reader.h +++ b/table/plain_table_reader.h @@ -57,6 +57,8 @@ class PlainTableReader: public TableReader { Iterator* NewIterator(const ReadOptions&, Arena* arena = nullptr) override; + void Prepare(const Slice& target); + Status Get(const ReadOptions&, const Slice& key, void* arg, bool (*result_handler)(void* arg, const ParsedInternalKey& k, const Slice& v, bool), diff --git a/table/table_reader.h b/table/table_reader.h index 9238b880c..dec0cac3f 100644 --- a/table/table_reader.h +++ b/table/table_reader.h @@ -49,6 +49,9 @@ class TableReader { virtual std::shared_ptr GetTableProperties() const = 0; + // Prepare work that can be done before the real Get() + virtual void Prepare(const Slice& target) {} + // Calls (*result_handler)(handle_context, ...) repeatedly, starting with // the entry found after a call to Seek(key), until result_handler returns // false, where k is the actual internal key for a row found and v as the diff --git a/util/dynamic_bloom.h b/util/dynamic_bloom.h index 2a0dc8434..4c4f7e1f9 100644 --- a/util/dynamic_bloom.h +++ b/util/dynamic_bloom.h @@ -5,12 +5,12 @@ #pragma once +#include +#include + #include #include -#include "port/port.h" -#include - namespace rocksdb { class Slice; @@ -53,6 +53,8 @@ class DynamicBloom { // Multithreaded access to this function is OK bool MayContainHash(uint32_t hash) const; + void Prefetch(uint32_t h); + private: uint32_t kTotalBits; uint32_t kNumBlocks; @@ -71,6 +73,13 @@ inline bool DynamicBloom::MayContain(const Slice& key) const { return (MayContainHash(hash_func_(key))); } +inline void DynamicBloom::Prefetch(uint32_t h) { + if (kNumBlocks != 0) { + uint32_t b = ((h >> 11 | (h << 21)) % kNumBlocks) * (CACHE_LINE_SIZE * 8); + PREFETCH(&(data_[b]), 0, 3); + } +} + inline bool DynamicBloom::MayContainHash(uint32_t h) const { assert(kNumBlocks > 0 || kTotalBits > 0); const uint32_t delta = (h >> 17) | (h << 15); // Rotate right 17 bits