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3dff28cf9b
Summary: For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>. The shared ptr has some performance degradation on certain hardware classes. For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere. For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it. The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource. There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold. In those cases, the shared pointer was preserved. Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17: 6.17: readrandom : 28.046 micros/op 854902 ops/sec; 61.3 MB/s (355999 of 355999 found) 6.18: readrandom : 32.615 micros/op 735306 ops/sec; 52.7 MB/s (290999 of 290999 found) PR: readrandom : 27.500 micros/op 871909 ops/sec; 62.5 MB/s (367999 of 367999 found) (Note that the times for 6.18 are prior to revert of the SystemClock). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033 Reviewed By: pdillinger Differential Revision: D27014563 Pulled By: mrambacher fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67
119 lines
3.5 KiB
C++
119 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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//
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#pragma once
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#include "monitoring/statistics.h"
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#include "rocksdb/system_clock.h"
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namespace ROCKSDB_NAMESPACE {
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// Auto-scoped.
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// Records the measure time into the corresponding histogram if statistics
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// is not nullptr. It is also saved into *elapsed if the pointer is not nullptr
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// and overwrite is true, it will be added to *elapsed if overwrite is false.
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class StopWatch {
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public:
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StopWatch(SystemClock* clock, Statistics* statistics,
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const uint32_t hist_type, uint64_t* elapsed = nullptr,
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bool overwrite = true, bool delay_enabled = false)
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: clock_(clock),
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statistics_(statistics),
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hist_type_(hist_type),
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elapsed_(elapsed),
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overwrite_(overwrite),
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stats_enabled_(statistics &&
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statistics->get_stats_level() >=
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StatsLevel::kExceptTimers &&
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statistics->HistEnabledForType(hist_type)),
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delay_enabled_(delay_enabled),
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total_delay_(0),
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delay_start_time_(0),
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start_time_((stats_enabled_ || elapsed != nullptr) ? clock->NowMicros()
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: 0) {}
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~StopWatch() {
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if (elapsed_) {
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if (overwrite_) {
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*elapsed_ = clock_->NowMicros() - start_time_;
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} else {
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*elapsed_ += clock_->NowMicros() - start_time_;
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}
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}
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if (elapsed_ && delay_enabled_) {
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*elapsed_ -= total_delay_;
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}
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if (stats_enabled_) {
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statistics_->reportTimeToHistogram(
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hist_type_, (elapsed_ != nullptr)
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? *elapsed_
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: (clock_->NowMicros() - start_time_));
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}
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}
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void DelayStart() {
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// if delay_start_time_ is not 0, it means we are already tracking delay,
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// so delay_start_time_ should not be overwritten
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if (elapsed_ && delay_enabled_ && delay_start_time_ == 0) {
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delay_start_time_ = clock_->NowMicros();
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}
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}
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void DelayStop() {
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if (elapsed_ && delay_enabled_ && delay_start_time_ != 0) {
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total_delay_ += clock_->NowMicros() - delay_start_time_;
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}
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// reset to 0 means currently no delay is being tracked, so two consecutive
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// calls to DelayStop will not increase total_delay_
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delay_start_time_ = 0;
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}
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uint64_t GetDelay() const { return delay_enabled_ ? total_delay_ : 0; }
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uint64_t start_time() const { return start_time_; }
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private:
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SystemClock* clock_;
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Statistics* statistics_;
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const uint32_t hist_type_;
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uint64_t* elapsed_;
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bool overwrite_;
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bool stats_enabled_;
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bool delay_enabled_;
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uint64_t total_delay_;
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uint64_t delay_start_time_;
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const uint64_t start_time_;
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};
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// a nano second precision stopwatch
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class StopWatchNano {
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public:
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explicit StopWatchNano(SystemClock* clock, bool auto_start = false)
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: clock_(clock), start_(0) {
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if (auto_start) {
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Start();
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}
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}
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void Start() { start_ = clock_->NowNanos(); }
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uint64_t ElapsedNanos(bool reset = false) {
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auto now = clock_->NowNanos();
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auto elapsed = now - start_;
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if (reset) {
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start_ = now;
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}
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return elapsed;
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}
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uint64_t ElapsedNanosSafe(bool reset = false) {
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return (clock_ != nullptr) ? ElapsedNanos(reset) : 0U;
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}
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private:
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SystemClock* clock_;
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uint64_t start_;
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};
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} // namespace ROCKSDB_NAMESPACE
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