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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 "bench.h"
24#include "futex.h"
25#include "cpumap.h"
26
27#include <err.h>
28#include <stdlib.h>
29#include <sys/time.h>
30
31/* all threads will block on the same futex */
32static u_int32_t futex1 = 0;
33
34/*
35 * How many wakeups to do at a time.
36 * Default to 1 in order to make the kernel work more.
37 */
38static unsigned int nwakes = 1;
39
40pthread_t *worker;
41static bool done = false, silent = false, fshared = false;
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;
46static int futex_flag = 0;
47
48static const struct option options[] = {
49 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
50 OPT_UINTEGER('w', "nwakes", &nwakes, "Specify amount of threads to wake at once"),
51 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
52 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
53 OPT_END()
54};
55
56static const char * const bench_futex_wake_usage[] = {
57 "perf bench futex wake <options>",
58 NULL
59};
60
61static void *workerfn(void *arg __maybe_unused)
62{
63 pthread_mutex_lock(&thread_lock);
64 threads_starting--;
65 if (!threads_starting)
66 pthread_cond_signal(&thread_parent);
67 pthread_cond_wait(&thread_worker, &thread_lock);
68 pthread_mutex_unlock(&thread_lock);
69
70 while (1) {
71 if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
72 break;
73 }
74
75 pthread_exit(NULL);
76 return NULL;
77}
78
79static void print_summary(void)
80{
81 double waketime_avg = avg_stats(&waketime_stats);
82 double waketime_stddev = stddev_stats(&waketime_stats);
83 unsigned int wakeup_avg = avg_stats(&wakeup_stats);
84
85 printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
86 wakeup_avg,
87 nthreads,
88 waketime_avg / USEC_PER_MSEC,
89 rel_stddev_stats(waketime_stddev, waketime_avg));
90}
91
92static void block_threads(pthread_t *w,
93 pthread_attr_t thread_attr, struct cpu_map *cpu)
94{
95 cpu_set_t cpuset;
96 unsigned int i;
97
98 threads_starting = nthreads;
99
100 /* create and block all threads */
101 for (i = 0; i < nthreads; i++) {
102 CPU_ZERO(&cpuset);
103 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
104
105 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
106 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
107
108 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
109 err(EXIT_FAILURE, "pthread_create");
110 }
111}
112
113static void toggle_done(int sig __maybe_unused,
114 siginfo_t *info __maybe_unused,
115 void *uc __maybe_unused)
116{
117 done = true;
118}
119
120int bench_futex_wake(int argc, const char **argv)
121{
122 int ret = 0;
123 unsigned int i, j;
124 struct sigaction act;
125 pthread_attr_t thread_attr;
126 struct cpu_map *cpu;
127
128 argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
129 if (argc) {
130 usage_with_options(bench_futex_wake_usage, options);
131 exit(EXIT_FAILURE);
132 }
133
134 cpu = cpu_map__new(NULL);
135 if (!cpu)
136 err(EXIT_FAILURE, "calloc");
137
138 sigfillset(&act.sa_mask);
139 act.sa_sigaction = toggle_done;
140 sigaction(SIGINT, &act, NULL);
141
142 if (!nthreads)
143 nthreads = ncpus;
144
145 worker = calloc(nthreads, sizeof(*worker));
146 if (!worker)
147 err(EXIT_FAILURE, "calloc");
148
149 if (!fshared)
150 futex_flag = FUTEX_PRIVATE_FLAG;
151
152 printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
153 "waking up %d at a time.\n\n",
154 getpid(), nthreads, fshared ? "shared":"private", &futex1, nwakes);
155
156 init_stats(&wakeup_stats);
157 init_stats(&waketime_stats);
158 pthread_attr_init(&thread_attr);
159 pthread_mutex_init(&thread_lock, NULL);
160 pthread_cond_init(&thread_parent, NULL);
161 pthread_cond_init(&thread_worker, NULL);
162
163 for (j = 0; j < bench_repeat && !done; j++) {
164 unsigned int nwoken = 0;
165 struct timeval start, end, runtime;
166
167 /* create, launch & block all threads */
168 block_threads(worker, thread_attr, cpu);
169
170 /* make sure all threads are already blocked */
171 pthread_mutex_lock(&thread_lock);
172 while (threads_starting)
173 pthread_cond_wait(&thread_parent, &thread_lock);
174 pthread_cond_broadcast(&thread_worker);
175 pthread_mutex_unlock(&thread_lock);
176
177 usleep(100000);
178
179 /* Ok, all threads are patiently blocked, start waking folks up */
180 gettimeofday(&start, NULL);
181 while (nwoken != nthreads)
182 nwoken += futex_wake(&futex1, nwakes, futex_flag);
183 gettimeofday(&end, NULL);
184 timersub(&end, &start, &runtime);
185
186 update_stats(&wakeup_stats, nwoken);
187 update_stats(&waketime_stats, runtime.tv_usec);
188
189 if (!silent) {
190 printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
191 j + 1, nwoken, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
192 }
193
194 for (i = 0; i < nthreads; i++) {
195 ret = pthread_join(worker[i], NULL);
196 if (ret)
197 err(EXIT_FAILURE, "pthread_join");
198 }
199
200 }
201
202 /* cleanup & report results */
203 pthread_cond_destroy(&thread_parent);
204 pthread_cond_destroy(&thread_worker);
205 pthread_mutex_destroy(&thread_lock);
206 pthread_attr_destroy(&thread_attr);
207
208 print_summary();
209
210 free(worker);
211 return ret;
212}
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/mutex.h"
18#include "../util/stat.h"
19#include <subcmd/parse-options.h>
20#include <linux/compiler.h>
21#include <linux/kernel.h>
22#include <linux/time64.h>
23#include <errno.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#include <sys/mman.h>
32
33/* all threads will block on the same futex */
34static u_int32_t futex1 = 0;
35
36static pthread_t *worker;
37static bool done = false;
38static struct mutex thread_lock;
39static struct cond thread_parent, thread_worker;
40static struct stats waketime_stats, wakeup_stats;
41static unsigned int threads_starting;
42static int futex_flag = 0;
43
44static struct bench_futex_parameters params = {
45 /*
46 * How many wakeups to do at a time.
47 * Default to 1 in order to make the kernel work more.
48 */
49 .nwakes = 1,
50};
51
52static const struct option options[] = {
53 OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
54 OPT_UINTEGER('w', "nwakes", ¶ms.nwakes, "Specify amount of threads to wake at once"),
55 OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"),
56 OPT_BOOLEAN( 'S', "shared", ¶ms.fshared, "Use shared futexes instead of private ones"),
57 OPT_BOOLEAN( 'm', "mlockall", ¶ms.mlockall, "Lock all current and future memory"),
58
59 OPT_END()
60};
61
62static const char * const bench_futex_wake_usage[] = {
63 "perf bench futex wake <options>",
64 NULL
65};
66
67static void *workerfn(void *arg __maybe_unused)
68{
69 mutex_lock(&thread_lock);
70 threads_starting--;
71 if (!threads_starting)
72 cond_signal(&thread_parent);
73 cond_wait(&thread_worker, &thread_lock);
74 mutex_unlock(&thread_lock);
75
76 while (1) {
77 if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
78 break;
79 }
80
81 pthread_exit(NULL);
82 return NULL;
83}
84
85static void print_summary(void)
86{
87 double waketime_avg = avg_stats(&waketime_stats);
88 double waketime_stddev = stddev_stats(&waketime_stats);
89 unsigned int wakeup_avg = avg_stats(&wakeup_stats);
90
91 printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
92 wakeup_avg,
93 params.nthreads,
94 waketime_avg / USEC_PER_MSEC,
95 rel_stddev_stats(waketime_stddev, waketime_avg));
96}
97
98static void block_threads(pthread_t *w,
99 pthread_attr_t thread_attr, struct perf_cpu_map *cpu)
100{
101 cpu_set_t *cpuset;
102 unsigned int i;
103 size_t size;
104 int nrcpus = perf_cpu_map__nr(cpu);
105 threads_starting = params.nthreads;
106
107 cpuset = CPU_ALLOC(nrcpus);
108 BUG_ON(!cpuset);
109 size = CPU_ALLOC_SIZE(nrcpus);
110
111 /* create and block all threads */
112 for (i = 0; i < params.nthreads; i++) {
113 CPU_ZERO_S(size, cpuset);
114 CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset);
115
116 if (pthread_attr_setaffinity_np(&thread_attr, size, cpuset)) {
117 CPU_FREE(cpuset);
118 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
119 }
120
121 if (pthread_create(&w[i], &thread_attr, workerfn, NULL)) {
122 CPU_FREE(cpuset);
123 err(EXIT_FAILURE, "pthread_create");
124 }
125 }
126 CPU_FREE(cpuset);
127}
128
129static void toggle_done(int sig __maybe_unused,
130 siginfo_t *info __maybe_unused,
131 void *uc __maybe_unused)
132{
133 done = true;
134}
135
136int bench_futex_wake(int argc, const char **argv)
137{
138 int ret = 0;
139 unsigned int i, j;
140 struct sigaction act;
141 pthread_attr_t thread_attr;
142 struct perf_cpu_map *cpu;
143
144 argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
145 if (argc) {
146 usage_with_options(bench_futex_wake_usage, options);
147 exit(EXIT_FAILURE);
148 }
149
150 cpu = perf_cpu_map__new(NULL);
151 if (!cpu)
152 err(EXIT_FAILURE, "calloc");
153
154 memset(&act, 0, sizeof(act));
155 sigfillset(&act.sa_mask);
156 act.sa_sigaction = toggle_done;
157 sigaction(SIGINT, &act, NULL);
158
159 if (params.mlockall) {
160 if (mlockall(MCL_CURRENT | MCL_FUTURE))
161 err(EXIT_FAILURE, "mlockall");
162 }
163
164 if (!params.nthreads)
165 params.nthreads = perf_cpu_map__nr(cpu);
166
167 worker = calloc(params.nthreads, sizeof(*worker));
168 if (!worker)
169 err(EXIT_FAILURE, "calloc");
170
171 if (!params.fshared)
172 futex_flag = FUTEX_PRIVATE_FLAG;
173
174 printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
175 "waking up %d at a time.\n\n",
176 getpid(), params.nthreads, params.fshared ? "shared":"private",
177 &futex1, params.nwakes);
178
179 init_stats(&wakeup_stats);
180 init_stats(&waketime_stats);
181 pthread_attr_init(&thread_attr);
182 mutex_init(&thread_lock);
183 cond_init(&thread_parent);
184 cond_init(&thread_worker);
185
186 for (j = 0; j < bench_repeat && !done; j++) {
187 unsigned int nwoken = 0;
188 struct timeval start, end, runtime;
189
190 /* create, launch & block all threads */
191 block_threads(worker, thread_attr, cpu);
192
193 /* make sure all threads are already blocked */
194 mutex_lock(&thread_lock);
195 while (threads_starting)
196 cond_wait(&thread_parent, &thread_lock);
197 cond_broadcast(&thread_worker);
198 mutex_unlock(&thread_lock);
199
200 usleep(100000);
201
202 /* Ok, all threads are patiently blocked, start waking folks up */
203 gettimeofday(&start, NULL);
204 while (nwoken != params.nthreads)
205 nwoken += futex_wake(&futex1,
206 params.nwakes, futex_flag);
207 gettimeofday(&end, NULL);
208 timersub(&end, &start, &runtime);
209
210 update_stats(&wakeup_stats, nwoken);
211 update_stats(&waketime_stats, runtime.tv_usec);
212
213 if (!params.silent) {
214 printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
215 j + 1, nwoken, params.nthreads,
216 runtime.tv_usec / (double)USEC_PER_MSEC);
217 }
218
219 for (i = 0; i < params.nthreads; i++) {
220 ret = pthread_join(worker[i], NULL);
221 if (ret)
222 err(EXIT_FAILURE, "pthread_join");
223 }
224
225 }
226
227 /* cleanup & report results */
228 cond_destroy(&thread_parent);
229 cond_destroy(&thread_worker);
230 mutex_destroy(&thread_lock);
231 pthread_attr_destroy(&thread_attr);
232
233 print_summary();
234
235 free(worker);
236 perf_cpu_map__put(cpu);
237 return ret;
238}