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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/* For the CLR_() macros */
12#include <pthread.h>
13
14#include <signal.h>
15#include "../util/stat.h"
16#include <subcmd/parse-options.h>
17#include <linux/compiler.h>
18#include <linux/kernel.h>
19#include <linux/time64.h>
20#include <errno.h>
21#include "bench.h"
22#include "futex.h"
23
24#include <err.h>
25#include <stdlib.h>
26#include <sys/time.h>
27
28/* all threads will block on the same futex */
29static u_int32_t futex1 = 0;
30
31/*
32 * How many wakeups to do at a time.
33 * Default to 1 in order to make the kernel work more.
34 */
35static unsigned int nwakes = 1;
36
37pthread_t *worker;
38static bool done = false, silent = false, fshared = false;
39static pthread_mutex_t thread_lock;
40static pthread_cond_t thread_parent, thread_worker;
41static struct stats waketime_stats, wakeup_stats;
42static unsigned int ncpus, threads_starting, nthreads = 0;
43static int futex_flag = 0;
44
45static const struct option options[] = {
46 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
47 OPT_UINTEGER('w', "nwakes", &nwakes, "Specify amount of threads to wake at once"),
48 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
49 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
50 OPT_END()
51};
52
53static const char * const bench_futex_wake_usage[] = {
54 "perf bench futex wake <options>",
55 NULL
56};
57
58static void *workerfn(void *arg __maybe_unused)
59{
60 pthread_mutex_lock(&thread_lock);
61 threads_starting--;
62 if (!threads_starting)
63 pthread_cond_signal(&thread_parent);
64 pthread_cond_wait(&thread_worker, &thread_lock);
65 pthread_mutex_unlock(&thread_lock);
66
67 while (1) {
68 if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
69 break;
70 }
71
72 pthread_exit(NULL);
73 return NULL;
74}
75
76static void print_summary(void)
77{
78 double waketime_avg = avg_stats(&waketime_stats);
79 double waketime_stddev = stddev_stats(&waketime_stats);
80 unsigned int wakeup_avg = avg_stats(&wakeup_stats);
81
82 printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
83 wakeup_avg,
84 nthreads,
85 waketime_avg / USEC_PER_MSEC,
86 rel_stddev_stats(waketime_stddev, waketime_avg));
87}
88
89static void block_threads(pthread_t *w,
90 pthread_attr_t thread_attr)
91{
92 cpu_set_t cpu;
93 unsigned int i;
94
95 threads_starting = nthreads;
96
97 /* create and block all threads */
98 for (i = 0; i < nthreads; i++) {
99 CPU_ZERO(&cpu);
100 CPU_SET(i % ncpus, &cpu);
101
102 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
103 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
104
105 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
106 err(EXIT_FAILURE, "pthread_create");
107 }
108}
109
110static void toggle_done(int sig __maybe_unused,
111 siginfo_t *info __maybe_unused,
112 void *uc __maybe_unused)
113{
114 done = true;
115}
116
117int bench_futex_wake(int argc, const char **argv,
118 const char *prefix __maybe_unused)
119{
120 int ret = 0;
121 unsigned int i, j;
122 struct sigaction act;
123 pthread_attr_t thread_attr;
124
125 argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
126 if (argc) {
127 usage_with_options(bench_futex_wake_usage, options);
128 exit(EXIT_FAILURE);
129 }
130
131 ncpus = sysconf(_SC_NPROCESSORS_ONLN);
132 nwakes = futexbench_sanitize_numeric(nwakes);
133
134 sigfillset(&act.sa_mask);
135 act.sa_sigaction = toggle_done;
136 sigaction(SIGINT, &act, NULL);
137
138 if (!nthreads)
139 nthreads = ncpus;
140 else
141 nthreads = futexbench_sanitize_numeric(nthreads);
142
143 worker = calloc(nthreads, sizeof(*worker));
144 if (!worker)
145 err(EXIT_FAILURE, "calloc");
146
147 if (!fshared)
148 futex_flag = FUTEX_PRIVATE_FLAG;
149
150 printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
151 "waking up %d at a time.\n\n",
152 getpid(), nthreads, fshared ? "shared":"private", &futex1, nwakes);
153
154 init_stats(&wakeup_stats);
155 init_stats(&waketime_stats);
156 pthread_attr_init(&thread_attr);
157 pthread_mutex_init(&thread_lock, NULL);
158 pthread_cond_init(&thread_parent, NULL);
159 pthread_cond_init(&thread_worker, NULL);
160
161 for (j = 0; j < bench_repeat && !done; j++) {
162 unsigned int nwoken = 0;
163 struct timeval start, end, runtime;
164
165 /* create, launch & block all threads */
166 block_threads(worker, thread_attr);
167
168 /* make sure all threads are already blocked */
169 pthread_mutex_lock(&thread_lock);
170 while (threads_starting)
171 pthread_cond_wait(&thread_parent, &thread_lock);
172 pthread_cond_broadcast(&thread_worker);
173 pthread_mutex_unlock(&thread_lock);
174
175 usleep(100000);
176
177 /* Ok, all threads are patiently blocked, start waking folks up */
178 gettimeofday(&start, NULL);
179 while (nwoken != nthreads)
180 nwoken += futex_wake(&futex1, nwakes, futex_flag);
181 gettimeofday(&end, NULL);
182 timersub(&end, &start, &runtime);
183
184 update_stats(&wakeup_stats, nwoken);
185 update_stats(&waketime_stats, runtime.tv_usec);
186
187 if (!silent) {
188 printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
189 j + 1, nwoken, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
190 }
191
192 for (i = 0; i < nthreads; i++) {
193 ret = pthread_join(worker[i], NULL);
194 if (ret)
195 err(EXIT_FAILURE, "pthread_join");
196 }
197
198 }
199
200 /* cleanup & report results */
201 pthread_cond_destroy(&thread_parent);
202 pthread_cond_destroy(&thread_worker);
203 pthread_mutex_destroy(&thread_lock);
204 pthread_attr_destroy(&thread_attr);
205
206 print_summary();
207
208 free(worker);
209 return ret;
210}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
4 *
5 * futex-wake: Block a bunch of threads on a futex and wake'em up, N at a time.
6 *
7 * This program is particularly useful to measure the latency of nthread wakeups
8 * in non-error situations: all waiters are queued and all wake calls wakeup
9 * one or more tasks, and thus the waitqueue is never empty.
10 */
11
12/* For the CLR_() macros */
13#include <string.h>
14#include <pthread.h>
15
16#include <signal.h>
17#include "../util/stat.h"
18#include <subcmd/parse-options.h>
19#include <linux/compiler.h>
20#include <linux/kernel.h>
21#include <linux/time64.h>
22#include <errno.h>
23#include <internal/cpumap.h>
24#include <perf/cpumap.h>
25#include "bench.h"
26#include "futex.h"
27
28#include <err.h>
29#include <stdlib.h>
30#include <sys/time.h>
31
32/* all threads will block on the same futex */
33static u_int32_t futex1 = 0;
34
35/*
36 * How many wakeups to do at a time.
37 * Default to 1 in order to make the kernel work more.
38 */
39static unsigned int nwakes = 1;
40
41pthread_t *worker;
42static bool done = false, silent = false, fshared = false;
43static pthread_mutex_t thread_lock;
44static pthread_cond_t thread_parent, thread_worker;
45static struct stats waketime_stats, wakeup_stats;
46static unsigned int ncpus, threads_starting, nthreads = 0;
47static int futex_flag = 0;
48
49static const struct option options[] = {
50 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
51 OPT_UINTEGER('w', "nwakes", &nwakes, "Specify amount of threads to wake at once"),
52 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
53 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
54 OPT_END()
55};
56
57static const char * const bench_futex_wake_usage[] = {
58 "perf bench futex wake <options>",
59 NULL
60};
61
62static void *workerfn(void *arg __maybe_unused)
63{
64 pthread_mutex_lock(&thread_lock);
65 threads_starting--;
66 if (!threads_starting)
67 pthread_cond_signal(&thread_parent);
68 pthread_cond_wait(&thread_worker, &thread_lock);
69 pthread_mutex_unlock(&thread_lock);
70
71 while (1) {
72 if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
73 break;
74 }
75
76 pthread_exit(NULL);
77 return NULL;
78}
79
80static void print_summary(void)
81{
82 double waketime_avg = avg_stats(&waketime_stats);
83 double waketime_stddev = stddev_stats(&waketime_stats);
84 unsigned int wakeup_avg = avg_stats(&wakeup_stats);
85
86 printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
87 wakeup_avg,
88 nthreads,
89 waketime_avg / USEC_PER_MSEC,
90 rel_stddev_stats(waketime_stddev, waketime_avg));
91}
92
93static void block_threads(pthread_t *w,
94 pthread_attr_t thread_attr, struct perf_cpu_map *cpu)
95{
96 cpu_set_t cpuset;
97 unsigned int i;
98
99 threads_starting = nthreads;
100
101 /* create and block all threads */
102 for (i = 0; i < nthreads; i++) {
103 CPU_ZERO(&cpuset);
104 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
105
106 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
107 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
108
109 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
110 err(EXIT_FAILURE, "pthread_create");
111 }
112}
113
114static void toggle_done(int sig __maybe_unused,
115 siginfo_t *info __maybe_unused,
116 void *uc __maybe_unused)
117{
118 done = true;
119}
120
121int bench_futex_wake(int argc, const char **argv)
122{
123 int ret = 0;
124 unsigned int i, j;
125 struct sigaction act;
126 pthread_attr_t thread_attr;
127 struct perf_cpu_map *cpu;
128
129 argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
130 if (argc) {
131 usage_with_options(bench_futex_wake_usage, options);
132 exit(EXIT_FAILURE);
133 }
134
135 cpu = perf_cpu_map__new(NULL);
136 if (!cpu)
137 err(EXIT_FAILURE, "calloc");
138
139 sigfillset(&act.sa_mask);
140 act.sa_sigaction = toggle_done;
141 sigaction(SIGINT, &act, NULL);
142
143 if (!nthreads)
144 nthreads = ncpus;
145
146 worker = calloc(nthreads, sizeof(*worker));
147 if (!worker)
148 err(EXIT_FAILURE, "calloc");
149
150 if (!fshared)
151 futex_flag = FUTEX_PRIVATE_FLAG;
152
153 printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
154 "waking up %d at a time.\n\n",
155 getpid(), nthreads, fshared ? "shared":"private", &futex1, nwakes);
156
157 init_stats(&wakeup_stats);
158 init_stats(&waketime_stats);
159 pthread_attr_init(&thread_attr);
160 pthread_mutex_init(&thread_lock, NULL);
161 pthread_cond_init(&thread_parent, NULL);
162 pthread_cond_init(&thread_worker, NULL);
163
164 for (j = 0; j < bench_repeat && !done; j++) {
165 unsigned int nwoken = 0;
166 struct timeval start, end, runtime;
167
168 /* create, launch & block all threads */
169 block_threads(worker, thread_attr, cpu);
170
171 /* make sure all threads are already blocked */
172 pthread_mutex_lock(&thread_lock);
173 while (threads_starting)
174 pthread_cond_wait(&thread_parent, &thread_lock);
175 pthread_cond_broadcast(&thread_worker);
176 pthread_mutex_unlock(&thread_lock);
177
178 usleep(100000);
179
180 /* Ok, all threads are patiently blocked, start waking folks up */
181 gettimeofday(&start, NULL);
182 while (nwoken != nthreads)
183 nwoken += futex_wake(&futex1, nwakes, futex_flag);
184 gettimeofday(&end, NULL);
185 timersub(&end, &start, &runtime);
186
187 update_stats(&wakeup_stats, nwoken);
188 update_stats(&waketime_stats, runtime.tv_usec);
189
190 if (!silent) {
191 printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
192 j + 1, nwoken, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
193 }
194
195 for (i = 0; i < nthreads; i++) {
196 ret = pthread_join(worker[i], NULL);
197 if (ret)
198 err(EXIT_FAILURE, "pthread_join");
199 }
200
201 }
202
203 /* cleanup & report results */
204 pthread_cond_destroy(&thread_parent);
205 pthread_cond_destroy(&thread_worker);
206 pthread_mutex_destroy(&thread_lock);
207 pthread_attr_destroy(&thread_attr);
208
209 print_summary();
210
211 free(worker);
212 return ret;
213}