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226 lines
5.9 KiB
226 lines
5.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2013 Davidlohr Bueso <[email protected]> |
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* |
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* futex-wake: Block a bunch of threads on a futex and wake'em up, N at a time. |
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* |
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* This program is particularly useful to measure the latency of nthread wakeups |
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* in non-error situations: all waiters are queued and all wake calls wakeup |
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* one or more tasks, and thus the waitqueue is never empty. |
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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 <perf/cpumap.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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#include <sys/mman.h> |
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/* all threads will block on the same futex */ |
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static u_int32_t futex1 = 0; |
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static pthread_t *worker; |
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static bool done = false; |
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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 threads_starting; |
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static int futex_flag = 0; |
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static struct bench_futex_parameters params = { |
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/* |
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* How many wakeups to do at a time. |
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* Default to 1 in order to make the kernel work more. |
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*/ |
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.nwakes = 1, |
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}; |
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static const struct option options[] = { |
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OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"), |
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OPT_UINTEGER('w', "nwakes", ¶ms.nwakes, "Specify amount of threads to wake at once"), |
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OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"), |
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OPT_BOOLEAN( 'S', "shared", ¶ms.fshared, "Use shared futexes instead of private ones"), |
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OPT_BOOLEAN( 'm', "mlockall", ¶ms.mlockall, "Lock all current and future memory"), |
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OPT_END() |
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}; |
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static const char * const bench_futex_wake_usage[] = { |
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"perf bench futex wake <options>", |
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NULL |
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}; |
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static void *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) { |
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if (futex_wait(&futex1, 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 print_summary(void) |
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{ |
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double waketime_avg = avg_stats(&waketime_stats); |
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double waketime_stddev = stddev_stats(&waketime_stats); |
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unsigned int wakeup_avg = avg_stats(&wakeup_stats); |
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printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n", |
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wakeup_avg, |
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params.nthreads, |
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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 block_threads(pthread_t *w, |
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pthread_attr_t thread_attr, struct perf_cpu_map *cpu) |
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{ |
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cpu_set_t cpuset; |
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unsigned int i; |
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threads_starting = params.nthreads; |
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/* create and block all threads */ |
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for (i = 0; i < params.nthreads; i++) { |
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CPU_ZERO(&cpuset); |
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CPU_SET(cpu->map[i % cpu->nr], &cpuset); |
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if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset)) |
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err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); |
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if (pthread_create(&w[i], &thread_attr, 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 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(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 perf_cpu_map *cpu; |
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argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0); |
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if (argc) { |
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usage_with_options(bench_futex_wake_usage, options); |
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exit(EXIT_FAILURE); |
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} |
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cpu = perf_cpu_map__new(NULL); |
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if (!cpu) |
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err(EXIT_FAILURE, "calloc"); |
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memset(&act, 0, sizeof(act)); |
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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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if (params.mlockall) { |
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if (mlockall(MCL_CURRENT | MCL_FUTURE)) |
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err(EXIT_FAILURE, "mlockall"); |
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} |
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if (!params.nthreads) |
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params.nthreads = cpu->nr; |
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worker = calloc(params.nthreads, sizeof(*worker)); |
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if (!worker) |
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err(EXIT_FAILURE, "calloc"); |
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if (!params.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] futex %p), " |
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"waking up %d at a time.\n\n", |
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getpid(), params.nthreads, params.fshared ? "shared":"private", |
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&futex1, params.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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unsigned int nwoken = 0; |
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struct timeval start, end, runtime; |
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/* create, launch & block all threads */ |
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block_threads(worker, thread_attr, cpu); |
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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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gettimeofday(&start, NULL); |
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while (nwoken != params.nthreads) |
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nwoken += futex_wake(&futex1, |
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params.nwakes, futex_flag); |
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gettimeofday(&end, NULL); |
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timersub(&end, &start, &runtime); |
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update_stats(&wakeup_stats, nwoken); |
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update_stats(&waketime_stats, runtime.tv_usec); |
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if (!params.silent) { |
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printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n", |
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j + 1, nwoken, params.nthreads, |
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runtime.tv_usec / (double)USEC_PER_MSEC); |
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} |
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for (i = 0; i < params.nthreads; i++) { |
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ret = pthread_join(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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} |
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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(worker); |
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return ret; |
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}
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