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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/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}
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}