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1/*
2 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
3 *
4 * futex-wake: Block a bunch of threads on a futex and wake'em up, N at a time.
5 *
6 * This program is particularly useful to measure the latency of nthread wakeups
7 * in non-error situations: all waiters are queued and all wake calls wakeup
8 * one or more tasks, and thus the waitqueue is never empty.
9 */
10
11#include "../perf.h"
12#include "../util/util.h"
13#include "../util/stat.h"
14#include "../util/parse-options.h"
15#include "../util/header.h"
16#include "bench.h"
17#include "futex.h"
18
19#include <err.h>
20#include <stdlib.h>
21#include <sys/time.h>
22#include <pthread.h>
23
24/* all threads will block on the same futex */
25static u_int32_t futex1 = 0;
26
27/*
28 * How many wakeups to do at a time.
29 * Default to 1 in order to make the kernel work more.
30 */
31static unsigned int nwakes = 1;
32
33/*
34 * There can be significant variance from run to run,
35 * the more repeats, the more exact the overall avg and
36 * the better idea of the futex latency.
37 */
38static unsigned int repeat = 10;
39
40pthread_t *worker;
41static bool done = 0, silent = 0;
42static pthread_mutex_t thread_lock;
43static pthread_cond_t thread_parent, thread_worker;
44static struct stats waketime_stats, wakeup_stats;
45static unsigned int ncpus, threads_starting, nthreads = 0;
46
47static const struct option options[] = {
48 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
49 OPT_UINTEGER('w', "nwakes", &nwakes, "Specify amount of threads to wake at once"),
50 OPT_UINTEGER('r', "repeat", &repeat, "Specify amount of times to repeat the run"),
51 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
52 OPT_END()
53};
54
55static const char * const bench_futex_wake_usage[] = {
56 "perf bench futex wake <options>",
57 NULL
58};
59
60static void *workerfn(void *arg __maybe_unused)
61{
62 pthread_mutex_lock(&thread_lock);
63 threads_starting--;
64 if (!threads_starting)
65 pthread_cond_signal(&thread_parent);
66 pthread_cond_wait(&thread_worker, &thread_lock);
67 pthread_mutex_unlock(&thread_lock);
68
69 futex_wait(&futex1, 0, NULL, FUTEX_PRIVATE_FLAG);
70 return NULL;
71}
72
73static void print_summary(void)
74{
75 double waketime_avg = avg_stats(&waketime_stats);
76 double waketime_stddev = stddev_stats(&waketime_stats);
77 unsigned int wakeup_avg = avg_stats(&wakeup_stats);
78
79 printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
80 wakeup_avg,
81 nthreads,
82 waketime_avg/1e3,
83 rel_stddev_stats(waketime_stddev, waketime_avg));
84}
85
86static void block_threads(pthread_t *w,
87 pthread_attr_t thread_attr)
88{
89 cpu_set_t cpu;
90 unsigned int i;
91
92 threads_starting = nthreads;
93
94 /* create and block all threads */
95 for (i = 0; i < nthreads; i++) {
96 CPU_ZERO(&cpu);
97 CPU_SET(i % ncpus, &cpu);
98
99 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
100 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
101
102 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
103 err(EXIT_FAILURE, "pthread_create");
104 }
105}
106
107static void toggle_done(int sig __maybe_unused,
108 siginfo_t *info __maybe_unused,
109 void *uc __maybe_unused)
110{
111 done = true;
112}
113
114int bench_futex_wake(int argc, const char **argv,
115 const char *prefix __maybe_unused)
116{
117 int ret = 0;
118 unsigned int i, j;
119 struct sigaction act;
120 pthread_attr_t thread_attr;
121
122 argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
123 if (argc) {
124 usage_with_options(bench_futex_wake_usage, options);
125 exit(EXIT_FAILURE);
126 }
127
128 ncpus = sysconf(_SC_NPROCESSORS_ONLN);
129
130 sigfillset(&act.sa_mask);
131 act.sa_sigaction = toggle_done;
132 sigaction(SIGINT, &act, NULL);
133
134 if (!nthreads)
135 nthreads = ncpus;
136
137 worker = calloc(nthreads, sizeof(*worker));
138 if (!worker)
139 err(EXIT_FAILURE, "calloc");
140
141 printf("Run summary [PID %d]: blocking on %d threads (at futex %p), "
142 "waking up %d at a time.\n\n",
143 getpid(), nthreads, &futex1, nwakes);
144
145 init_stats(&wakeup_stats);
146 init_stats(&waketime_stats);
147 pthread_attr_init(&thread_attr);
148 pthread_mutex_init(&thread_lock, NULL);
149 pthread_cond_init(&thread_parent, NULL);
150 pthread_cond_init(&thread_worker, NULL);
151
152 for (j = 0; j < repeat && !done; j++) {
153 unsigned int nwoken = 0;
154 struct timeval start, end, runtime;
155
156 /* create, launch & block all threads */
157 block_threads(worker, thread_attr);
158
159 /* make sure all threads are already blocked */
160 pthread_mutex_lock(&thread_lock);
161 while (threads_starting)
162 pthread_cond_wait(&thread_parent, &thread_lock);
163 pthread_cond_broadcast(&thread_worker);
164 pthread_mutex_unlock(&thread_lock);
165
166 usleep(100000);
167
168 /* Ok, all threads are patiently blocked, start waking folks up */
169 gettimeofday(&start, NULL);
170 while (nwoken != nthreads)
171 nwoken += futex_wake(&futex1, nwakes, FUTEX_PRIVATE_FLAG);
172 gettimeofday(&end, NULL);
173 timersub(&end, &start, &runtime);
174
175 update_stats(&wakeup_stats, nwoken);
176 update_stats(&waketime_stats, runtime.tv_usec);
177
178 if (!silent) {
179 printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
180 j + 1, nwoken, nthreads, runtime.tv_usec/1e3);
181 }
182
183 for (i = 0; i < nthreads; i++) {
184 ret = pthread_join(worker[i], NULL);
185 if (ret)
186 err(EXIT_FAILURE, "pthread_join");
187 }
188
189 }
190
191 /* cleanup & report results */
192 pthread_cond_destroy(&thread_parent);
193 pthread_cond_destroy(&thread_worker);
194 pthread_mutex_destroy(&thread_lock);
195 pthread_attr_destroy(&thread_attr);
196
197 print_summary();
198
199 free(worker);
200 return ret;
201}
1/*
2 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
3 *
4 * futex-wake: Block a bunch of threads on a futex and wake'em up, N at a time.
5 *
6 * This program is particularly useful to measure the latency of nthread wakeups
7 * in non-error situations: all waiters are queued and all wake calls wakeup
8 * one or more tasks, and thus the waitqueue is never empty.
9 */
10
11#include "../perf.h"
12#include "../util/util.h"
13#include "../util/stat.h"
14#include <subcmd/parse-options.h>
15#include "../util/header.h"
16#include "bench.h"
17#include "futex.h"
18
19#include <err.h>
20#include <stdlib.h>
21#include <sys/time.h>
22#include <pthread.h>
23
24/* all threads will block on the same futex */
25static u_int32_t futex1 = 0;
26
27/*
28 * How many wakeups to do at a time.
29 * Default to 1 in order to make the kernel work more.
30 */
31static unsigned int nwakes = 1;
32
33pthread_t *worker;
34static bool done = false, silent = false, fshared = false;
35static pthread_mutex_t thread_lock;
36static pthread_cond_t thread_parent, thread_worker;
37static struct stats waketime_stats, wakeup_stats;
38static unsigned int ncpus, threads_starting, nthreads = 0;
39static int futex_flag = 0;
40
41static const struct option options[] = {
42 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
43 OPT_UINTEGER('w', "nwakes", &nwakes, "Specify amount of threads to wake at once"),
44 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
45 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
46 OPT_END()
47};
48
49static const char * const bench_futex_wake_usage[] = {
50 "perf bench futex wake <options>",
51 NULL
52};
53
54static void *workerfn(void *arg __maybe_unused)
55{
56 pthread_mutex_lock(&thread_lock);
57 threads_starting--;
58 if (!threads_starting)
59 pthread_cond_signal(&thread_parent);
60 pthread_cond_wait(&thread_worker, &thread_lock);
61 pthread_mutex_unlock(&thread_lock);
62
63 while (1) {
64 if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
65 break;
66 }
67
68 pthread_exit(NULL);
69 return NULL;
70}
71
72static void print_summary(void)
73{
74 double waketime_avg = avg_stats(&waketime_stats);
75 double waketime_stddev = stddev_stats(&waketime_stats);
76 unsigned int wakeup_avg = avg_stats(&wakeup_stats);
77
78 printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
79 wakeup_avg,
80 nthreads,
81 waketime_avg/1e3,
82 rel_stddev_stats(waketime_stddev, waketime_avg));
83}
84
85static void block_threads(pthread_t *w,
86 pthread_attr_t thread_attr)
87{
88 cpu_set_t cpu;
89 unsigned int i;
90
91 threads_starting = nthreads;
92
93 /* create and block all threads */
94 for (i = 0; i < nthreads; i++) {
95 CPU_ZERO(&cpu);
96 CPU_SET(i % ncpus, &cpu);
97
98 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
99 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
100
101 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
102 err(EXIT_FAILURE, "pthread_create");
103 }
104}
105
106static void toggle_done(int sig __maybe_unused,
107 siginfo_t *info __maybe_unused,
108 void *uc __maybe_unused)
109{
110 done = true;
111}
112
113int bench_futex_wake(int argc, const char **argv,
114 const char *prefix __maybe_unused)
115{
116 int ret = 0;
117 unsigned int i, j;
118 struct sigaction act;
119 pthread_attr_t thread_attr;
120
121 argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
122 if (argc) {
123 usage_with_options(bench_futex_wake_usage, options);
124 exit(EXIT_FAILURE);
125 }
126
127 ncpus = sysconf(_SC_NPROCESSORS_ONLN);
128
129 sigfillset(&act.sa_mask);
130 act.sa_sigaction = toggle_done;
131 sigaction(SIGINT, &act, NULL);
132
133 if (!nthreads)
134 nthreads = ncpus;
135
136 worker = calloc(nthreads, sizeof(*worker));
137 if (!worker)
138 err(EXIT_FAILURE, "calloc");
139
140 if (!fshared)
141 futex_flag = FUTEX_PRIVATE_FLAG;
142
143 printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
144 "waking up %d at a time.\n\n",
145 getpid(), nthreads, fshared ? "shared":"private", &futex1, nwakes);
146
147 init_stats(&wakeup_stats);
148 init_stats(&waketime_stats);
149 pthread_attr_init(&thread_attr);
150 pthread_mutex_init(&thread_lock, NULL);
151 pthread_cond_init(&thread_parent, NULL);
152 pthread_cond_init(&thread_worker, NULL);
153
154 for (j = 0; j < bench_repeat && !done; j++) {
155 unsigned int nwoken = 0;
156 struct timeval start, end, runtime;
157
158 /* create, launch & block all threads */
159 block_threads(worker, thread_attr);
160
161 /* make sure all threads are already blocked */
162 pthread_mutex_lock(&thread_lock);
163 while (threads_starting)
164 pthread_cond_wait(&thread_parent, &thread_lock);
165 pthread_cond_broadcast(&thread_worker);
166 pthread_mutex_unlock(&thread_lock);
167
168 usleep(100000);
169
170 /* Ok, all threads are patiently blocked, start waking folks up */
171 gettimeofday(&start, NULL);
172 while (nwoken != nthreads)
173 nwoken += futex_wake(&futex1, nwakes, futex_flag);
174 gettimeofday(&end, NULL);
175 timersub(&end, &start, &runtime);
176
177 update_stats(&wakeup_stats, nwoken);
178 update_stats(&waketime_stats, runtime.tv_usec);
179
180 if (!silent) {
181 printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
182 j + 1, nwoken, nthreads, runtime.tv_usec/1e3);
183 }
184
185 for (i = 0; i < nthreads; i++) {
186 ret = pthread_join(worker[i], NULL);
187 if (ret)
188 err(EXIT_FAILURE, "pthread_join");
189 }
190
191 }
192
193 /* cleanup & report results */
194 pthread_cond_destroy(&thread_parent);
195 pthread_cond_destroy(&thread_worker);
196 pthread_mutex_destroy(&thread_lock);
197 pthread_attr_destroy(&thread_attr);
198
199 print_summary();
200
201 free(worker);
202 return ret;
203}