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925d8252e5
Summary:
RocksDB's jemalloc no-dump allocator (`NewJemallocNodumpAllocator()`) was using a single manual arena. This arena's lock contention could be very high when thread caching is disabled for RocksDB blocks (e.g., when using `MALLOC_CONF='tcache_max:4096'` and `rocksdb_block_size=16384`).
This PR changes the jemalloc no-dump allocator to use a configurable number of manual arenas. That number is required to be a power of two so we can avoid division. The allocator shards allocation requests randomly across those manual arenas.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11400
Test Plan:
- mysqld setup
- Branch: fb-mysql-8.0.28 (653eba2e56)
- Build: `mysqlbuild.sh --clean --release`
- Set env var `MALLOC_CONF='tcache_max:$tcache_max'`
- Added CLI args `--rocksdb_cache_dump=false --rocksdb_block_cache_size=4294967296 --rocksdb_block_size=16384`
- Ran under /usr/bin/time
- Large database scenario
- Setup command: `mysqlslap -h 127.0.0.1 -P 13020 --auto-generate-sql=1 --auto-generate-sql-load-type=write --auto-generate-sql-guid-primary=1 --number-char-cols=8 --auto-generate-sql-execute-number=262144 --concurrency=32 --no-drop`
- Benchmark command: `mysqlslap -h 127.0.0.1 -P 13020 --query='select count(*) from mysqlslap.t1;' --number-of-queries=320 --concurrency=32`
- Results:
| tcache_max | num_arenas | Peak RSS MB (% change) | Query latency seconds (% change) |
|---|---|---|---|
| 4096 | **(baseline)** | 4541 | 37.1 |
| 4096 | 1 | 4535 (-0.1%) | 36.7 (-1%) |
| 4096 | 8 | 4687 (+3%) | 10.2 (-73%) |
| 16384 | **(baseline)** | 4514 | 8.4 |
| 16384 | 1 | 4526 (+0.3%) | 8.5 (+1%) |
| 16384 | 8 | 4580 (+1%) | 8.5 (+1%) |
Reviewed By: pdillinger
Differential Revision: D45220794
Pulled By: ajkr
fbshipit-source-id: 9a50c9872bdef5d299e52b115a65ee8a5557d58d
100 lines
3.5 KiB
C++
100 lines
3.5 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include <atomic>
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#include <vector>
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#include "port/jemalloc_helper.h"
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#include "port/port.h"
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#include "rocksdb/memory_allocator.h"
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#include "util/thread_local.h"
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#include "utilities/memory_allocators.h"
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#if defined(ROCKSDB_JEMALLOC) && defined(ROCKSDB_PLATFORM_POSIX)
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#include <sys/mman.h>
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#if (JEMALLOC_VERSION_MAJOR >= 5) && defined(MADV_DONTDUMP)
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#define ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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#endif // (JEMALLOC_VERSION_MAJOR >= 5) && MADV_DONTDUMP
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#endif // ROCKSDB_JEMALLOC && ROCKSDB_PLATFORM_POSIX
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namespace ROCKSDB_NAMESPACE {
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// Allocation requests are randomly sharded across
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// `JemallocAllocatorOptions::num_arenas` arenas to reduce contention on per-
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// arena mutexes.
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class JemallocNodumpAllocator : public BaseMemoryAllocator {
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public:
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explicit JemallocNodumpAllocator(JemallocAllocatorOptions& options);
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#ifdef ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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~JemallocNodumpAllocator();
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#endif // ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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static const char* kClassName() { return "JemallocNodumpAllocator"; }
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const char* Name() const override { return kClassName(); }
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static bool IsSupported() {
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std::string unused;
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return IsSupported(&unused);
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}
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static bool IsSupported(std::string* why);
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bool IsMutable() const { return !init_; }
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Status PrepareOptions(const ConfigOptions& config_options) override;
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#ifdef ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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void* Allocate(size_t size) override;
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void Deallocate(void* p) override;
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size_t UsableSize(void* p, size_t allocation_size) const override;
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#endif // ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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private:
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#ifdef ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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Status InitializeArenas();
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uint32_t GetArenaIndex() const;
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// Custom alloc hook to replace jemalloc default alloc.
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static void* Alloc(extent_hooks_t* extent, void* new_addr, size_t size,
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size_t alignment, bool* zero, bool* commit,
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unsigned arena_ind);
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// Destroy arena on destruction of the allocator, or on failure.
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static Status DestroyArena(uint32_t arena_index);
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// Destroy tcache on destruction of the allocator, or thread exit.
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static void DestroyThreadSpecificCache(void* ptr);
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// Get or create tcache. Return flag suitable to use with `mallocx`:
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// either MALLOCX_TCACHE_NONE or MALLOCX_TCACHE(tc).
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int GetThreadSpecificCache(size_t size);
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#endif // ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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JemallocAllocatorOptions options_;
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#ifdef ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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// A function pointer to jemalloc default alloc. Use atomic to make sure
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// NewJemallocNodumpAllocator is thread-safe.
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//
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// Hack: original_alloc_ needs to be static for Alloc() to access it.
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// alloc needs to be static to pass to jemalloc as function pointer. We can
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// use a single process-wide value as long as we assume that any newly created
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// arena has the same original value in its `alloc` function pointer.
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static std::atomic<extent_alloc_t*> original_alloc_;
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// Custom hooks has to outlive corresponding arena.
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std::vector<std::unique_ptr<extent_hooks_t>> per_arena_hooks_;
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// Hold thread-local tcache index.
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ThreadLocalPtr tcache_;
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std::vector<uint32_t> arena_indexes_;
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#endif // ROCKSDB_JEMALLOC_NODUMP_ALLOCATOR
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bool init_ = false;
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};
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} // namespace ROCKSDB_NAMESPACE
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