mirror of https://gitee.com/openkylin/linux.git
299 lines
7.9 KiB
C
299 lines
7.9 KiB
C
/*
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* Copyright (C) 2015 Davidlohr Bueso.
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*
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* Block a bunch of threads and let parallel waker threads wakeup an
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* equal amount of them. The program output reflects the avg latency
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* for each individual thread to service its share of work. Ultimately
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* it can be used to measure futex_wake() changes.
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*/
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/* For the CLR_() macros */
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#include <string.h>
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#include <pthread.h>
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#include <signal.h>
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#include "../util/stat.h"
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#include <subcmd/parse-options.h>
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#include <linux/compiler.h>
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#include <linux/kernel.h>
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#include <linux/time64.h>
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#include <errno.h>
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#include "bench.h"
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#include "futex.h"
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#include <err.h>
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#include <stdlib.h>
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#include <sys/time.h>
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struct thread_data {
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pthread_t worker;
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unsigned int nwoken;
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struct timeval runtime;
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};
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static unsigned int nwakes = 1;
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/* all threads will block on the same futex -- hash bucket chaos ;) */
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static u_int32_t futex = 0;
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static pthread_t *blocked_worker;
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static bool done = false, silent = false, fshared = false;
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static unsigned int nblocked_threads = 0, nwaking_threads = 0;
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static pthread_mutex_t thread_lock;
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static pthread_cond_t thread_parent, thread_worker;
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static struct stats waketime_stats, wakeup_stats;
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static unsigned int ncpus, threads_starting;
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static int futex_flag = 0;
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static const struct option options[] = {
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OPT_UINTEGER('t', "threads", &nblocked_threads, "Specify amount of threads"),
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OPT_UINTEGER('w', "nwakers", &nwaking_threads, "Specify amount of waking threads"),
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OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
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OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
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OPT_END()
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};
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static const char * const bench_futex_wake_parallel_usage[] = {
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"perf bench futex wake-parallel <options>",
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NULL
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};
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static void *waking_workerfn(void *arg)
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{
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struct thread_data *waker = (struct thread_data *) arg;
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struct timeval start, end;
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gettimeofday(&start, NULL);
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waker->nwoken = futex_wake(&futex, nwakes, futex_flag);
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if (waker->nwoken != nwakes)
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warnx("couldn't wakeup all tasks (%d/%d)",
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waker->nwoken, nwakes);
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gettimeofday(&end, NULL);
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timersub(&end, &start, &waker->runtime);
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pthread_exit(NULL);
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return NULL;
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}
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static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr)
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{
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unsigned int i;
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pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE);
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/* create and block all threads */
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for (i = 0; i < nwaking_threads; i++) {
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/*
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* Thread creation order will impact per-thread latency
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* as it will affect the order to acquire the hb spinlock.
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* For now let the scheduler decide.
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*/
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if (pthread_create(&td[i].worker, &thread_attr,
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waking_workerfn, (void *)&td[i]))
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err(EXIT_FAILURE, "pthread_create");
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}
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for (i = 0; i < nwaking_threads; i++)
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if (pthread_join(td[i].worker, NULL))
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err(EXIT_FAILURE, "pthread_join");
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}
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static void *blocked_workerfn(void *arg __maybe_unused)
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{
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pthread_mutex_lock(&thread_lock);
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threads_starting--;
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if (!threads_starting)
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pthread_cond_signal(&thread_parent);
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pthread_cond_wait(&thread_worker, &thread_lock);
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pthread_mutex_unlock(&thread_lock);
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while (1) { /* handle spurious wakeups */
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if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR)
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break;
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}
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pthread_exit(NULL);
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return NULL;
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}
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static void block_threads(pthread_t *w, pthread_attr_t thread_attr)
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{
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cpu_set_t cpu;
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unsigned int i;
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threads_starting = nblocked_threads;
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/* create and block all threads */
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for (i = 0; i < nblocked_threads; i++) {
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CPU_ZERO(&cpu);
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CPU_SET(i % ncpus, &cpu);
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if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
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err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
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if (pthread_create(&w[i], &thread_attr, blocked_workerfn, NULL))
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err(EXIT_FAILURE, "pthread_create");
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}
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}
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static void print_run(struct thread_data *waking_worker, unsigned int run_num)
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{
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unsigned int i, wakeup_avg;
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double waketime_avg, waketime_stddev;
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struct stats __waketime_stats, __wakeup_stats;
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init_stats(&__wakeup_stats);
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init_stats(&__waketime_stats);
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for (i = 0; i < nwaking_threads; i++) {
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update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec);
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update_stats(&__wakeup_stats, waking_worker[i].nwoken);
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}
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waketime_avg = avg_stats(&__waketime_stats);
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waketime_stddev = stddev_stats(&__waketime_stats);
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wakeup_avg = avg_stats(&__wakeup_stats);
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printf("[Run %d]: Avg per-thread latency (waking %d/%d threads) "
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"in %.4f ms (+-%.2f%%)\n", run_num + 1, wakeup_avg,
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nblocked_threads, waketime_avg / USEC_PER_MSEC,
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rel_stddev_stats(waketime_stddev, waketime_avg));
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}
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static void print_summary(void)
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{
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unsigned int wakeup_avg;
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double waketime_avg, waketime_stddev;
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waketime_avg = avg_stats(&waketime_stats);
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waketime_stddev = stddev_stats(&waketime_stats);
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wakeup_avg = avg_stats(&wakeup_stats);
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printf("Avg per-thread latency (waking %d/%d threads) in %.4f ms (+-%.2f%%)\n",
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wakeup_avg,
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nblocked_threads,
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waketime_avg / USEC_PER_MSEC,
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rel_stddev_stats(waketime_stddev, waketime_avg));
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}
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static void do_run_stats(struct thread_data *waking_worker)
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{
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unsigned int i;
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for (i = 0; i < nwaking_threads; i++) {
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update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec);
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update_stats(&wakeup_stats, waking_worker[i].nwoken);
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}
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}
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static void toggle_done(int sig __maybe_unused,
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siginfo_t *info __maybe_unused,
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void *uc __maybe_unused)
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{
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done = true;
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}
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int bench_futex_wake_parallel(int argc, const char **argv)
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{
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int ret = 0;
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unsigned int i, j;
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struct sigaction act;
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pthread_attr_t thread_attr;
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struct thread_data *waking_worker;
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argc = parse_options(argc, argv, options,
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bench_futex_wake_parallel_usage, 0);
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if (argc) {
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usage_with_options(bench_futex_wake_parallel_usage, options);
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exit(EXIT_FAILURE);
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}
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sigfillset(&act.sa_mask);
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act.sa_sigaction = toggle_done;
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sigaction(SIGINT, &act, NULL);
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ncpus = sysconf(_SC_NPROCESSORS_ONLN);
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if (!nblocked_threads)
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nblocked_threads = ncpus;
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/* some sanity checks */
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if (nwaking_threads > nblocked_threads || !nwaking_threads)
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nwaking_threads = nblocked_threads;
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if (nblocked_threads % nwaking_threads)
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errx(EXIT_FAILURE, "Must be perfectly divisible");
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/*
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* Each thread will wakeup nwakes tasks in
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* a single futex_wait call.
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*/
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nwakes = nblocked_threads/nwaking_threads;
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blocked_worker = calloc(nblocked_threads, sizeof(*blocked_worker));
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if (!blocked_worker)
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err(EXIT_FAILURE, "calloc");
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if (!fshared)
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futex_flag = FUTEX_PRIVATE_FLAG;
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printf("Run summary [PID %d]: blocking on %d threads (at [%s] "
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"futex %p), %d threads waking up %d at a time.\n\n",
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getpid(), nblocked_threads, fshared ? "shared":"private",
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&futex, nwaking_threads, nwakes);
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init_stats(&wakeup_stats);
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init_stats(&waketime_stats);
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pthread_attr_init(&thread_attr);
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pthread_mutex_init(&thread_lock, NULL);
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pthread_cond_init(&thread_parent, NULL);
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pthread_cond_init(&thread_worker, NULL);
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for (j = 0; j < bench_repeat && !done; j++) {
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waking_worker = calloc(nwaking_threads, sizeof(*waking_worker));
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if (!waking_worker)
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err(EXIT_FAILURE, "calloc");
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/* create, launch & block all threads */
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block_threads(blocked_worker, thread_attr);
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/* make sure all threads are already blocked */
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pthread_mutex_lock(&thread_lock);
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while (threads_starting)
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pthread_cond_wait(&thread_parent, &thread_lock);
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pthread_cond_broadcast(&thread_worker);
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pthread_mutex_unlock(&thread_lock);
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usleep(100000);
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/* Ok, all threads are patiently blocked, start waking folks up */
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wakeup_threads(waking_worker, thread_attr);
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for (i = 0; i < nblocked_threads; i++) {
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ret = pthread_join(blocked_worker[i], NULL);
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if (ret)
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err(EXIT_FAILURE, "pthread_join");
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}
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do_run_stats(waking_worker);
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if (!silent)
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print_run(waking_worker, j);
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free(waking_worker);
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}
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/* cleanup & report results */
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pthread_cond_destroy(&thread_parent);
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pthread_cond_destroy(&thread_worker);
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pthread_mutex_destroy(&thread_lock);
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pthread_attr_destroy(&thread_attr);
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print_summary();
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free(blocked_worker);
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return ret;
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}
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