1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // UNSUPPORTED: c++03, c++11, c++14, c++17 10 11 #include <atomic> 12 #include <cstdint> 13 #include <mutex> 14 #include <stop_token> 15 #include <thread> 16 17 #include "benchmark/benchmark.h" 18 #include "make_test_thread.h" 19 20 using namespace std::chrono_literals; 21 22 struct AtomicLock { 23 std::atomic<bool>& locked_; 24 25 AtomicLock(const AtomicLock&) = delete; 26 AtomicLock& operator=(const AtomicLock&) = delete; 27 28 AtomicLock(std::atomic<bool>& l) : locked_(l) { lock(); } 29 ~AtomicLock() { unlock(); } 30 31 void lock() { 32 while (true) { 33 locked_.wait(true, std::memory_order_relaxed); 34 bool expected = false; 35 if (locked_.compare_exchange_weak(expected, true, std::memory_order_acquire, std::memory_order_relaxed)) 36 break; 37 } 38 } 39 40 void unlock() { 41 locked_.store(false, std::memory_order_release); 42 locked_.notify_all(); 43 } 44 }; 45 46 // using LockState = std::atomic<bool>; 47 // using Lock = AtomicLock; 48 49 // using LockState = std::mutex; 50 // using Lock = std::unique_lock<std::mutex>; 51 52 template <class LockState, class Lock> 53 void test_multi_thread_lock_unlock(benchmark::State& state) { 54 std::uint64_t total_loop_test_param = state.range(0); 55 constexpr auto num_threads = 15; 56 std::vector<std::jthread> threads; 57 threads.reserve(num_threads); 58 59 std::atomic<std::uint64_t> start_flag = 0; 60 std::atomic<std::uint64_t> done_count = 0; 61 62 LockState lock_state{}; 63 64 auto func = [&start_flag, &done_count, &lock_state, total_loop_test_param](std::stop_token st) { 65 auto old_start = 0; 66 while (!st.stop_requested()) { 67 start_flag.wait(old_start); 68 old_start = start_flag.load(); 69 70 // main things under test: locking and unlocking in the loop 71 for (std::uint64_t i = 0; i < total_loop_test_param; ++i) { 72 Lock l{lock_state}; 73 } 74 75 done_count.fetch_add(1); 76 } 77 }; 78 79 for (size_t i = 0; i < num_threads; ++i) { 80 threads.emplace_back(support::make_test_jthread(func)); 81 } 82 83 for (auto _ : state) { 84 done_count = 0; 85 start_flag.fetch_add(1); 86 start_flag.notify_all(); 87 while (done_count < num_threads) { 88 std::this_thread::yield(); 89 } 90 } 91 for (auto& t : threads) { 92 t.request_stop(); 93 } 94 start_flag.fetch_add(1); 95 start_flag.notify_all(); 96 for (auto& t : threads) { 97 t.join(); 98 } 99 } 100 101 void BM_atomic_wait(benchmark::State& state) { test_multi_thread_lock_unlock<std::atomic<bool>, AtomicLock>(state); } 102 BENCHMARK(BM_atomic_wait)->RangeMultiplier(2)->Range(1 << 10, 1 << 20); 103 104 void BM_mutex(benchmark::State& state) { 105 test_multi_thread_lock_unlock<std::mutex, std::unique_lock<std::mutex>>(state); 106 } 107 BENCHMARK(BM_mutex)->RangeMultiplier(2)->Range(1 << 10, 1 << 20); 108 109 BENCHMARK_MAIN(); 110