1026e794a3
Summary: Dynamic adjustment of rate limit according to demand for background I/O. It increases by a factor when limiter is drained too frequently, and decreases by the same factor when limiter is not drained frequently enough. The parameters for this behavior are fixed in `GenericRateLimiter::Tune`. Other changes: - make rate limiter's `Env*` configurable for testing - track num drain intervals in RateLimiter so we don't have to rely on stats, which may be shared across different DB instances from the ones that share the RateLimiter. Closes https://github.com/facebook/rocksdb/pull/2899 Differential Revision: D5858704 Pulled By: ajkr fbshipit-source-id: cc2bac30f85e7f6fd63655d0a6732ef9ed7403b1
114 lines
3.3 KiB
C++
114 lines
3.3 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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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <algorithm>
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#include <atomic>
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#include <chrono>
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#include <deque>
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#include "port/port.h"
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#include "rocksdb/env.h"
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#include "rocksdb/rate_limiter.h"
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#include "util/mutexlock.h"
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#include "util/random.h"
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namespace rocksdb {
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class GenericRateLimiter : public RateLimiter {
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public:
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GenericRateLimiter(int64_t refill_bytes, int64_t refill_period_us,
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int32_t fairness, RateLimiter::Mode mode, Env* env,
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bool auto_tuned);
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virtual ~GenericRateLimiter();
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// This API allows user to dynamically change rate limiter's bytes per second.
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virtual void SetBytesPerSecond(int64_t bytes_per_second) override;
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// Request for token to write bytes. If this request can not be satisfied,
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// the call is blocked. Caller is responsible to make sure
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// bytes <= GetSingleBurstBytes()
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using RateLimiter::Request;
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virtual void Request(const int64_t bytes, const Env::IOPriority pri,
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Statistics* stats) override;
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virtual int64_t GetSingleBurstBytes() const override {
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return refill_bytes_per_period_.load(std::memory_order_relaxed);
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}
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virtual int64_t GetTotalBytesThrough(
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const Env::IOPriority pri = Env::IO_TOTAL) const override {
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MutexLock g(&request_mutex_);
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if (pri == Env::IO_TOTAL) {
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return total_bytes_through_[Env::IO_LOW] +
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total_bytes_through_[Env::IO_HIGH];
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}
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return total_bytes_through_[pri];
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}
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virtual int64_t GetTotalRequests(
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const Env::IOPriority pri = Env::IO_TOTAL) const override {
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MutexLock g(&request_mutex_);
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if (pri == Env::IO_TOTAL) {
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return total_requests_[Env::IO_LOW] + total_requests_[Env::IO_HIGH];
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}
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return total_requests_[pri];
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}
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virtual int64_t GetBytesPerSecond() const override {
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return rate_bytes_per_sec_;
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}
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private:
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void Refill();
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int64_t CalculateRefillBytesPerPeriod(int64_t rate_bytes_per_sec);
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Status Tune();
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uint64_t NowMicrosMonotonic(Env* env) {
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return env->NowNanos() / std::milli::den;
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}
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// This mutex guard all internal states
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mutable port::Mutex request_mutex_;
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const int64_t kMinRefillBytesPerPeriod = 100;
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const int64_t refill_period_us_;
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int64_t rate_bytes_per_sec_;
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// This variable can be changed dynamically.
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std::atomic<int64_t> refill_bytes_per_period_;
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Env* const env_;
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bool stop_;
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port::CondVar exit_cv_;
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int32_t requests_to_wait_;
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int64_t total_requests_[Env::IO_TOTAL];
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int64_t total_bytes_through_[Env::IO_TOTAL];
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int64_t available_bytes_;
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int64_t next_refill_us_;
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int32_t fairness_;
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Random rnd_;
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struct Req;
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Req* leader_;
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std::deque<Req*> queue_[Env::IO_TOTAL];
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bool auto_tuned_;
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int64_t num_drains_;
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int64_t prev_num_drains_;
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const int64_t max_bytes_per_sec_;
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std::chrono::microseconds tuned_time_;
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};
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} // namespace rocksdb
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