1b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes/* 2b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * Copyright (C) 2014 The Android Open Source Project 3b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * 4b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * Licensed under the Apache License, Version 2.0 (the "License"); 5b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * you may not use this file except in compliance with the License. 6b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * You may obtain a copy of the License at 7b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * 8b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * http://www.apache.org/licenses/LICENSE-2.0 9b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * 10b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * Unless required by applicable law or agreed to in writing, software 11b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * distributed under the License is distributed on an "AS IS" BASIS, 12b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * See the License for the specific language governing permissions and 14b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes * limitations under the License. 15b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes */ 16b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes 177e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn#include <pthread.h> 18b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes#include <semaphore.h> 197e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn#include <stdatomic.h> 207e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn#include <stdio.h> 21a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes#include <stdlib.h> 22b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes 23a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes#include <benchmark/benchmark.h> 24df4942c04a63ae6e4f5c78ece9f696d6b8b74d32Christopher Ferris 25a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughesstatic void BM_semaphore_sem_getvalue(benchmark::State& state) { 26b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_t semaphore; 27b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_init(&semaphore, 1, 1); 28b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes 29a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes while (state.KeepRunning()) { 30b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes int dummy; 31b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_getvalue(&semaphore, &dummy); 32b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes } 33b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes} 34a630784fe1124ae5956da2639f1b324c15365fa7Elliott HughesBENCHMARK(BM_semaphore_sem_getvalue); 35b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes 36a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughesstatic void BM_semaphore_sem_wait_sem_post(benchmark::State& state) { 37b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_t semaphore; 38b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_init(&semaphore, 1, 1); 39b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes 40a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes while (state.KeepRunning()) { 41b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_wait(&semaphore); 42b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes sem_post(&semaphore); 43b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes } 44b28e490b7350b21c5ae9e5b3bb3e082d8357a1b0Elliott Hughes} 45a630784fe1124ae5956da2639f1b324c15365fa7Elliott HughesBENCHMARK(BM_semaphore_sem_wait_sem_post); 46a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 47a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// This test reports the overhead of the underlying futex wake syscall on 48a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// the producer. It does not report the overhead from issuing the wake to the 49a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// point where the posted consumer thread wakes up. It suffers from 50a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// clock_gettime syscall overhead. Lock the CPU speed for consistent results 51a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// as we may not reach >50% cpu utilization. 52a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// 53a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// We will run a background thread that catches the sem_post wakeup and 54a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// loops immediately returning back to sleep in sem_wait for the next one. This 55a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// thread is run with policy SCHED_OTHER (normal policy), a middle policy. 56a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// 57a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// The primary thread will run at SCHED_IDLE (lowest priority policy) when 58a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// monitoring the background thread to detect when it hits sem_wait sleep. It 59a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// will do so with no clock running. Once we are ready, we will switch to 60a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// SCHED_FIFO (highest priority policy) to time the act of running sem_post 61a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// with the benchmark clock running. This ensures nothing else in the system 62a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// can preempt our timed activity, including the background thread. We are 63a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// also protected with the scheduling policy of letting a process hit a 64a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// resource limit rather than get hit with a context switch. 65a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// 66a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// The background thread will start executing either on another CPU, or 67a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// after we back down from SCHED_FIFO, but certainly not in the context of 68a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes// the timing of the sem_post. 697e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn 707e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzynstatic atomic_int BM_semaphore_sem_post_running; 717e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn 72a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughesstatic void* BM_semaphore_sem_post_start_thread(void* arg) { 73a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sem_t* semaphore = reinterpret_cast<sem_t*>(arg); 74a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes while ((BM_semaphore_sem_post_running > 0) && !sem_wait(semaphore)) { 75a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes } 76a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes BM_semaphore_sem_post_running = -1; 77a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes return NULL; 787e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn} 797e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn 80a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughesclass SemaphoreFixture : public benchmark::Fixture { 81a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes public: 82a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes void SetUp(const benchmark::State&) { 83a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sem_init(&semaphore, 0, 0); 84a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 85a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_attr_t attr; 86a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_attr_init(&attr); 87a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 88a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes memset(¶m, 0, sizeof(param)); 89a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_attr_setschedparam(&attr, ¶m); 90a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_attr_setschedpolicy(&attr, SCHED_OTHER); 91a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); 92a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_t pthread; 93a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_create(&pthread, &attr, BM_semaphore_sem_post_start_thread, &semaphore); 94a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes pthread_attr_destroy(&attr); 95a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 96a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_setscheduler(0, SCHED_IDLE, ¶m); 97a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 98a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes BM_semaphore_sem_post_running = 1; 99a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes } 100a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 101a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes ~SemaphoreFixture() { 102a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_setscheduler(0, SCHED_OTHER, ¶m); 103a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 104a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes if (BM_semaphore_sem_post_running > 0) { 105a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes BM_semaphore_sem_post_running = 0; 106a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes } 107a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes do { 108a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sem_post(&semaphore); 109a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_yield(); 110a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes } while (BM_semaphore_sem_post_running != -1); 111a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes } 1127e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn 1137e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn sem_t semaphore; 114a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_param param; 115a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes}; 116a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 117a630784fe1124ae5956da2639f1b324c15365fa7Elliott HughesBENCHMARK_F(SemaphoreFixture, semaphore_sem_post)(benchmark::State& state) { 118a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes while (state.KeepRunning()) { 119a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes state.PauseTiming(); 120a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 1217e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn int trys = 3, dummy = 0; 1227e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn do { 1237e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn if (BM_semaphore_sem_post_running < 0) { 124a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_setscheduler(0, SCHED_OTHER, ¶m); 1257e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn fprintf(stderr, "BM_semaphore_sem_post: start_thread died unexpectedly\n"); 126a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes abort(); 1277e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn } 1287e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn sched_yield(); 1297e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn sem_getvalue(&semaphore, &dummy); 1307e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn if (dummy < 0) { // POSIX.1-2001 possibility 1 1317e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn break; 1327e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn } 1337e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn if (dummy == 0) { // POSIX.1-2001 possibility 2 1347e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn --trys; 1357e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn } 1367e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn } while (trys); 137a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 1387e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn param.sched_priority = 1; 139a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_setscheduler(0, SCHED_FIFO, ¶m); 140a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes 141a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes state.ResumeTiming(); 1427e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn sem_post(&semaphore); 1437e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn 144a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes param.sched_priority = 0; 145a630784fe1124ae5956da2639f1b324c15365fa7Elliott Hughes sched_setscheduler(0, SCHED_IDLE, ¶m); 1467e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn } 1477e50fb2a681c858ec7d85ff92e97794f41fd1f08Mark Salyzyn} 148