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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 <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}
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}