| 1 | //===----------------------------------------------------------------------===// |
|---|---|
| 2 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 3 | // See https://llvm.org/LICENSE.txt for license information. |
| 4 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 5 | // |
| 6 | //===----------------------------------------------------------------------===// |
| 7 | |
| 8 | // This benchmark compares the performance of std::mutex and std::shared_mutex in contended scenarios. |
| 9 | // it's meant to establish a baseline overhead for std::shared_mutex and std::mutex, and to help inform decisions about |
| 10 | // which mutex to use when selecting a mutex type for a given use case. |
| 11 | |
| 12 | #include <atomic> |
| 13 | #include <mutex> |
| 14 | #include <numeric> |
| 15 | #include <shared_mutex> |
| 16 | #include <thread> |
| 17 | |
| 18 | #include "benchmark/benchmark.h" |
| 19 | |
| 20 | int global_value = 42; |
| 21 | std::mutex m; |
| 22 | std::shared_mutex sm; |
| 23 | |
| 24 | static void BM_shared_mutex(benchmark::State& state) { |
| 25 | for (auto _ : state) { |
| 26 | std::shared_lock<std::shared_mutex> lock(sm); |
| 27 | benchmark::DoNotOptimize(value&: global_value); |
| 28 | } |
| 29 | } |
| 30 | |
| 31 | static void BM_mutex(benchmark::State& state) { |
| 32 | for (auto _ : state) { |
| 33 | std::lock_guard<std::mutex> lock(m); |
| 34 | benchmark::DoNotOptimize(value&: global_value); |
| 35 | } |
| 36 | } |
| 37 | |
| 38 | BENCHMARK(BM_shared_mutex)->Threads(t: 1)->Threads(t: 2)->Threads(t: 4)->Threads(t: 8)->Threads(t: 32); |
| 39 | BENCHMARK(BM_mutex)->Threads(t: 1)->Threads(t: 2)->Threads(t: 4)->Threads(t: 8)->Threads(t: 32); |
| 40 | |
| 41 | BENCHMARK_MAIN(); |
| 42 |