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Diffstat (limited to 'src/mongo/db/query/query_stats/rate_limiting_bm.cpp')
| -rw-r--r-- | src/mongo/db/query/query_stats/rate_limiting_bm.cpp | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/src/mongo/db/query/query_stats/rate_limiting_bm.cpp b/src/mongo/db/query/query_stats/rate_limiting_bm.cpp new file mode 100644 index 00000000000..06308e6b0d8 --- /dev/null +++ b/src/mongo/db/query/query_stats/rate_limiting_bm.cpp @@ -0,0 +1,144 @@ +/** + * Copyright (C) 2023-present MongoDB, Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the Server Side Public License, version 1, + * as published by MongoDB, Inc. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * Server Side Public License for more details. + * + * You should have received a copy of the Server Side Public License + * along with this program. If not, see + * <http://www.mongodb.com/licensing/server-side-public-license>. + * + * As a special exception, the copyright holders give permission to link the + * code of portions of this program with the OpenSSL library under certain + * conditions as described in each individual source file and distribute + * linked combinations including the program with the OpenSSL library. You + * must comply with the Server Side Public License in all respects for + * all of the code used other than as permitted herein. If you modify file(s) + * with this exception, you may extend this exception to your version of the + * file(s), but you are not obligated to do so. If you do not wish to do so, + * delete this exception statement from your version. If you delete this + * exception statement from all source files in the program, then also delete + * it in the license file. + */ + + +#include <benchmark/benchmark.h> +#include <climits> +#include <memory> + +#include "mongo/bson/json.h" +#include "mongo/db/matcher/expression_leaf.h" +#include "mongo/db/matcher/expression_parser.h" +#include "mongo/db/query/query_shape/query_shape.h" +#include "mongo/db/query/query_stats/rate_limiting.h" +#include "mongo/util/duration.h" +#include "mongo/util/processinfo.h" +#include "mongo/util/time_support.h" + +namespace mongo { +namespace { + +// Local testing determined that these parameter values drove the most lock contention, which is +// what we want to capture in this benchmark. +constexpr long long rateLimitedWorkTimeMicros = 5; +constexpr long long consistentWorkTimeMicros = 10; + +constexpr long long numThreads = 256; + +// Rate limit some fraction of the overall work for a request with a sliding window. +int requestWithSlidingWindow(RateLimiting& limit) { + if (limit.handleRequestSlidingWindow()) { + sleepmicros(rateLimitedWorkTimeMicros); + } + sleepmicros(consistentWorkTimeMicros); + return 0; +} + +// Represent a request that bypasses the rate limiter. +int requestUnlimited() { + constexpr long long totalTime = rateLimitedWorkTimeMicros + consistentWorkTimeMicros; + sleepmicros(totalTime); + return 0; +} + +// Represent a request without the rate limited work. +int requestDeactivated() { + sleepmicros(consistentWorkTimeMicros); + return 0; +} + +// Benchmark sliding window rate limiting. +void BM_SlidingWindow(benchmark::State& state) { + // The rate limiter needs a clock source passed in. + static std::unique_ptr<ClockSource> clockSource; + static std::unique_ptr<RateLimiting> rateLimit; + + // Initialize the rate limiter only on the first thread to start up. + if (state.thread_index == 0) { + clockSource = std::make_unique<SystemClockSource>(); + rateLimit = + std::make_unique<RateLimiting>(state.range(0), Milliseconds(1), clockSource.get()); + } + + // Run the benchmark. + for (auto keepRunning : state) { + benchmark::DoNotOptimize(requestWithSlidingWindow(*rateLimit)); + } + + // Clean up the rate limiter when the benchmark is done. + if (state.thread_index == 0) { + rateLimit.reset(); + clockSource.reset(); + } +} + +// "Control" benchmark that does not rate limit requests. In other words, the extra work is always +// done for every request. This benchmark can be thought of as the "goal" performance for the peak, +// or the highest rate limit in BM_SlidingWindow, to compare against. +void BM_Unlimited(benchmark::State& state) { + for (auto keepRunning : state) { + benchmark::DoNotOptimize(requestUnlimited()); + } +} +// Another control benchmark, where the extra work is never done for any request. This can be +// thought of as the goal performance for when rate limit equals 0. +void BM_Deactivated(benchmark::State& state) { + for (auto keepRunning : state) { + benchmark::DoNotOptimize(requestDeactivated()); + } +} + +// Google microbenchmarks report time T (in nanoseconds) spent per operation. But at Mongo we are +// interested in total opereations performed per second. The former can easily be converted to the +// latter by diving 10^6 by T. Use this benchmark to determine the natural throughput of the +// operation. This can be compared to the rate limited benchmarks (BM_SlidingWindow) to determine +// the overhead of rate limiting. Looking at the percentage change in throughput between the control +// benchmarks and the rate limited benchmark, will indicate how much overhead is due to lock +// contention. +BENCHMARK(BM_Unlimited)->Threads(numThreads); + +BENCHMARK(BM_Deactivated)->Threads(numThreads); + +// Local testing has confirmed that the higher the rate limit, the worse the throughput. This makes +// sense as putting a higher upper bound on number of requests allowed in a given time period, means +// longer wait times for the lock. +BENCHMARK(BM_SlidingWindow) + ->ArgName("rate limit") + ->Arg(0) + ->Arg(64) + ->Arg(128) + ->Arg(256) + ->Arg(512) + ->Arg(1024) + ->Arg(2048) + ->Arg(4816) + ->Threads(numThreads); + +} // namespace +} // namespace mongo |
