// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com> * * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing. * * This program is particularly useful for measuring the kernel's futex hash * table/function implementation. In order for it to make sense, use with as * many threads and futexes as possible. */ /* For the CLR_() macros */ #include <string.h> #include <pthread.h> #include <errno.h> #include <signal.h> #include <stdlib.h> #include <linux/compiler.h> #include <linux/kernel.h> #include <linux/zalloc.h> #include <sys/time.h> #include <perf/cpumap.h> #include "../util/stat.h" #include <subcmd/parse-options.h> #include "bench.h" #include "futex.h" #include <err.h> static unsigned int nthreads = 0; static unsigned int nsecs = 10; /* amount of futexes per thread */ static unsigned int nfutexes = 1024; static bool fshared = false, done = false, silent = false; static int futex_flag = 0; struct timeval bench__start, bench__end, bench__runtime; static pthread_mutex_t thread_lock; static unsigned int threads_starting; static struct stats throughput_stats; static pthread_cond_t thread_parent, thread_worker; struct worker { int tid; u_int32_t *futex; pthread_t thread; unsigned long ops; }; static const struct option options[] = { OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"), OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"), OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"), OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"), OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"), OPT_END() }; static const char * const bench_futex_hash_usage[] = { "perf bench futex hash <options>", NULL }; static void *workerfn(void *arg) { int ret; struct worker *w = (struct worker *) arg; unsigned int i; unsigned long ops = w->ops; /* avoid cacheline bouncing */ pthread_mutex_lock(&thread_lock); threads_starting--; if (!threads_starting) pthread_cond_signal(&thread_parent); pthread_cond_wait(&thread_worker, &thread_lock); pthread_mutex_unlock(&thread_lock); do { for (i = 0; i < nfutexes; i++, ops++) { /* * We want the futex calls to fail in order to stress * the hashing of uaddr and not measure other steps, * such as internal waitqueue handling, thus enlarging * the critical region protected by hb->lock. */ ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag); if (!silent && (!ret || errno != EAGAIN || errno != EWOULDBLOCK)) warn("Non-expected futex return call"); } } while (!done); w->ops = ops; return NULL; } static void toggle_done(int sig __maybe_unused, siginfo_t *info __maybe_unused, void *uc __maybe_unused) { /* inform all threads that we're done for the day */ done = true; gettimeofday(&bench__end, NULL); timersub(&bench__end, &bench__start, &bench__runtime); } static void print_summary(void) { unsigned long avg = avg_stats(&throughput_stats); double stddev = stddev_stats(&throughput_stats); printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), (int)bench__runtime.tv_sec); } int bench_futex_hash(int argc, const char **argv) { int ret = 0; cpu_set_t cpuset; struct sigaction act; unsigned int i; pthread_attr_t thread_attr; struct worker *worker = NULL; struct perf_cpu_map *cpu; argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0); if (argc) { usage_with_options(bench_futex_hash_usage, options); exit(EXIT_FAILURE); } cpu = perf_cpu_map__new(NULL); if (!cpu) goto errmem; memset(&act, 0, sizeof(act)); sigfillset(&act.sa_mask); act.sa_sigaction = toggle_done; sigaction(SIGINT, &act, NULL); if (!nthreads) /* default to the number of CPUs */ nthreads = cpu->nr; worker = calloc(nthreads, sizeof(*worker)); if (!worker) goto errmem; if (!fshared) futex_flag = FUTEX_PRIVATE_FLAG; printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs); init_stats(&throughput_stats); pthread_mutex_init(&thread_lock, NULL); pthread_cond_init(&thread_parent, NULL); pthread_cond_init(&thread_worker, NULL); threads_starting = nthreads; pthread_attr_init(&thread_attr); gettimeofday(&bench__start, NULL); for (i = 0; i < nthreads; i++) { worker[i].tid = i; worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex)); if (!worker[i].futex) goto errmem; CPU_ZERO(&cpuset); CPU_SET(cpu->map[i % cpu->nr], &cpuset); ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset); if (ret) err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); ret = pthread_create(&worker[i].thread, &thread_attr, workerfn, (void *)(struct worker *) &worker[i]); if (ret) err(EXIT_FAILURE, "pthread_create"); } pthread_attr_destroy(&thread_attr); pthread_mutex_lock(&thread_lock); while (threads_starting) pthread_cond_wait(&thread_parent, &thread_lock); pthread_cond_broadcast(&thread_worker); pthread_mutex_unlock(&thread_lock); sleep(nsecs); toggle_done(0, NULL, NULL); for (i = 0; i < nthreads; i++) { ret = pthread_join(worker[i].thread, NULL); if (ret) err(EXIT_FAILURE, "pthread_join"); } /* cleanup & report results */ pthread_cond_destroy(&thread_parent); pthread_cond_destroy(&thread_worker); pthread_mutex_destroy(&thread_lock); for (i = 0; i < nthreads; i++) { unsigned long t = bench__runtime.tv_sec > 0 ? worker[i].ops / bench__runtime.tv_sec : 0; update_stats(&throughput_stats, t); if (!silent) { if (nfutexes == 1) printf("[thread %2d] futex: %p [ %ld ops/sec ]\n", worker[i].tid, &worker[i].futex[0], t); else printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n", worker[i].tid, &worker[i].futex[0], &worker[i].futex[nfutexes-1], t); } zfree(&worker[i].futex); } print_summary(); free(worker); free(cpu); return ret; errmem: err(EXIT_FAILURE, "calloc"); }