2 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
4 * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
6 * This program is particularly useful for measuring the kernel's futex hash
7 * table/function implementation. In order for it to make sense, use with as
8 * many threads and futexes as possible.
12 #include "../util/util.h"
13 #include "../util/stat.h"
14 #include "../util/parse-options.h"
15 #include "../util/header.h"
24 static unsigned int nthreads = 0;
25 static unsigned int nsecs = 10;
26 /* amount of futexes per thread */
27 static unsigned int nfutexes = 1024;
28 static bool fshared = false, done = false, silent = false;
30 struct timeval start, end, runtime;
31 static pthread_mutex_t thread_lock;
32 static unsigned int threads_starting;
33 static struct stats throughput_stats;
34 static pthread_cond_t thread_parent, thread_worker;
43 static const struct option options[] = {
44 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
45 OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"),
46 OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"),
47 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
48 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
52 static const char * const bench_futex_hash_usage[] = {
53 "perf bench futex hash <options>",
57 static void *workerfn(void *arg)
61 struct worker *w = (struct worker *) arg;
63 pthread_mutex_lock(&thread_lock);
65 if (!threads_starting)
66 pthread_cond_signal(&thread_parent);
67 pthread_cond_wait(&thread_worker, &thread_lock);
68 pthread_mutex_unlock(&thread_lock);
71 for (i = 0; i < nfutexes; i++, w->ops++) {
73 * We want the futex calls to fail in order to stress
74 * the hashing of uaddr and not measure other steps,
75 * such as internal waitqueue handling, thus enlarging
76 * the critical region protected by hb->lock.
78 ret = futex_wait(&w->futex[i], 1234, NULL,
79 fshared ? 0 : FUTEX_PRIVATE_FLAG);
81 (!ret || errno != EAGAIN || errno != EWOULDBLOCK))
82 warn("Non-expected futex return call");
89 static void toggle_done(int sig __maybe_unused,
90 siginfo_t *info __maybe_unused,
91 void *uc __maybe_unused)
93 /* inform all threads that we're done for the day */
95 gettimeofday(&end, NULL);
96 timersub(&end, &start, &runtime);
99 static void print_summary(void)
101 unsigned long avg = avg_stats(&throughput_stats);
102 double stddev = stddev_stats(&throughput_stats);
104 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
105 !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
106 (int) runtime.tv_sec);
109 int bench_futex_hash(int argc, const char **argv,
110 const char *prefix __maybe_unused)
114 struct sigaction act;
115 unsigned int i, ncpus;
116 pthread_attr_t thread_attr;
117 struct worker *worker = NULL;
119 argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0);
121 usage_with_options(bench_futex_hash_usage, options);
125 ncpus = sysconf(_SC_NPROCESSORS_ONLN);
127 sigfillset(&act.sa_mask);
128 act.sa_sigaction = toggle_done;
129 sigaction(SIGINT, &act, NULL);
131 if (!nthreads) /* default to the number of CPUs */
134 worker = calloc(nthreads, sizeof(*worker));
138 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
139 getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs);
141 init_stats(&throughput_stats);
142 pthread_mutex_init(&thread_lock, NULL);
143 pthread_cond_init(&thread_parent, NULL);
144 pthread_cond_init(&thread_worker, NULL);
146 threads_starting = nthreads;
147 pthread_attr_init(&thread_attr);
148 gettimeofday(&start, NULL);
149 for (i = 0; i < nthreads; i++) {
151 worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex));
152 if (!worker[i].futex)
156 CPU_SET(i % ncpus, &cpu);
158 ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu);
160 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
162 ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
163 (void *)(struct worker *) &worker[i]);
165 err(EXIT_FAILURE, "pthread_create");
168 pthread_attr_destroy(&thread_attr);
170 pthread_mutex_lock(&thread_lock);
171 while (threads_starting)
172 pthread_cond_wait(&thread_parent, &thread_lock);
173 pthread_cond_broadcast(&thread_worker);
174 pthread_mutex_unlock(&thread_lock);
177 toggle_done(0, NULL, NULL);
179 for (i = 0; i < nthreads; i++) {
180 ret = pthread_join(worker[i].thread, NULL);
182 err(EXIT_FAILURE, "pthread_join");
185 /* cleanup & report results */
186 pthread_cond_destroy(&thread_parent);
187 pthread_cond_destroy(&thread_worker);
188 pthread_mutex_destroy(&thread_lock);
190 for (i = 0; i < nthreads; i++) {
191 unsigned long t = worker[i].ops/runtime.tv_sec;
192 update_stats(&throughput_stats, t);
195 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
196 worker[i].tid, &worker[i].futex[0], t);
198 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
199 worker[i].tid, &worker[i].futex[0],
200 &worker[i].futex[nfutexes-1], t);
203 free(worker[i].futex);
211 err(EXIT_FAILURE, "calloc");