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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
4 *
5 * futex-requeue: Block a bunch of threads on futex1 and requeue them
6 * on futex2, N at a time.
7 *
8 * This program is particularly useful to measure the latency of nthread
9 * requeues without waking up any tasks -- thus mimicking a regular futex_wait.
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
31static u_int32_t futex1 = 0, futex2 = 0;
32
33/*
34 * How many tasks to requeue at a time.
35 * Default to 1 in order to make the kernel work more.
36 */
37static unsigned int nrequeue = 1;
38
39static pthread_t *worker;
40static bool done = false, silent = false, fshared = false;
41static pthread_mutex_t thread_lock;
42static pthread_cond_t thread_parent, thread_worker;
43static struct stats requeuetime_stats, requeued_stats;
44static unsigned int threads_starting, nthreads = 0;
45static int futex_flag = 0;
46
47static const struct option options[] = {
48 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
49 OPT_UINTEGER('q', "nrequeue", &nrequeue, "Specify amount of threads to requeue at once"),
50 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
51 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
52 OPT_END()
53};
54
55static const char * const bench_futex_requeue_usage[] = {
56 "perf bench futex requeue <options>",
57 NULL
58};
59
60static void print_summary(void)
61{
62 double requeuetime_avg = avg_stats(&requeuetime_stats);
63 double requeuetime_stddev = stddev_stats(&requeuetime_stats);
64 unsigned int requeued_avg = avg_stats(&requeued_stats);
65
66 printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n",
67 requeued_avg,
68 nthreads,
69 requeuetime_avg / USEC_PER_MSEC,
70 rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
71}
72
73static void *workerfn(void *arg __maybe_unused)
74{
75 pthread_mutex_lock(&thread_lock);
76 threads_starting--;
77 if (!threads_starting)
78 pthread_cond_signal(&thread_parent);
79 pthread_cond_wait(&thread_worker, &thread_lock);
80 pthread_mutex_unlock(&thread_lock);
81
82 futex_wait(&futex1, 0, NULL, futex_flag);
83 return NULL;
84}
85
86static void block_threads(pthread_t *w,
87 pthread_attr_t thread_attr, struct cpu_map *cpu)
88{
89 cpu_set_t cpuset;
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(&cpuset);
97 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
98
99 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
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_requeue(int argc, const char **argv)
115{
116 int ret = 0;
117 unsigned int i, j;
118 struct sigaction act;
119 pthread_attr_t thread_attr;
120 struct cpu_map *cpu;
121
122 argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0);
123 if (argc)
124 goto err;
125
126 cpu = cpu_map__new(NULL);
127 if (!cpu)
128 err(EXIT_FAILURE, "cpu_map__new");
129
130 sigfillset(&act.sa_mask);
131 act.sa_sigaction = toggle_done;
132 sigaction(SIGINT, &act, NULL);
133
134 if (!nthreads)
135 nthreads = cpu->nr;
136
137 worker = calloc(nthreads, sizeof(*worker));
138 if (!worker)
139 err(EXIT_FAILURE, "calloc");
140
141 if (!fshared)
142 futex_flag = FUTEX_PRIVATE_FLAG;
143
144 if (nrequeue > nthreads)
145 nrequeue = nthreads;
146
147 printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %p), "
148 "%d at a time.\n\n", getpid(), nthreads,
149 fshared ? "shared":"private", &futex1, &futex2, nrequeue);
150
151 init_stats(&requeued_stats);
152 init_stats(&requeuetime_stats);
153 pthread_attr_init(&thread_attr);
154 pthread_mutex_init(&thread_lock, NULL);
155 pthread_cond_init(&thread_parent, NULL);
156 pthread_cond_init(&thread_worker, NULL);
157
158 for (j = 0; j < bench_repeat && !done; j++) {
159 unsigned int nrequeued = 0;
160 struct timeval start, end, runtime;
161
162 /* create, launch & block all threads */
163 block_threads(worker, thread_attr, cpu);
164
165 /* make sure all threads are already blocked */
166 pthread_mutex_lock(&thread_lock);
167 while (threads_starting)
168 pthread_cond_wait(&thread_parent, &thread_lock);
169 pthread_cond_broadcast(&thread_worker);
170 pthread_mutex_unlock(&thread_lock);
171
172 usleep(100000);
173
174 /* Ok, all threads are patiently blocked, start requeueing */
175 gettimeofday(&start, NULL);
176 while (nrequeued < nthreads) {
177 /*
178 * Do not wakeup any tasks blocked on futex1, allowing
179 * us to really measure futex_wait functionality.
180 */
181 nrequeued += futex_cmp_requeue(&futex1, 0, &futex2, 0,
182 nrequeue, futex_flag);
183 }
184
185 gettimeofday(&end, NULL);
186 timersub(&end, &start, &runtime);
187
188 update_stats(&requeued_stats, nrequeued);
189 update_stats(&requeuetime_stats, runtime.tv_usec);
190
191 if (!silent) {
192 printf("[Run %d]: Requeued %d of %d threads in %.4f ms\n",
193 j + 1, nrequeued, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
194 }
195
196 /* everybody should be blocked on futex2, wake'em up */
197 nrequeued = futex_wake(&futex2, nrequeued, futex_flag);
198 if (nthreads != nrequeued)
199 warnx("couldn't wakeup all tasks (%d/%d)", nrequeued, nthreads);
200
201 for (i = 0; i < nthreads; i++) {
202 ret = pthread_join(worker[i], NULL);
203 if (ret)
204 err(EXIT_FAILURE, "pthread_join");
205 }
206 }
207
208 /* cleanup & report results */
209 pthread_cond_destroy(&thread_parent);
210 pthread_cond_destroy(&thread_worker);
211 pthread_mutex_destroy(&thread_lock);
212 pthread_attr_destroy(&thread_attr);
213
214 print_summary();
215
216 free(worker);
217 return ret;
218err:
219 usage_with_options(bench_futex_requeue_usage, options);
220 exit(EXIT_FAILURE);
221}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
4 *
5 * futex-requeue: Block a bunch of threads on futex1 and requeue them
6 * on futex2, N at a time.
7 *
8 * This program is particularly useful to measure the latency of nthread
9 * requeues without waking up any tasks (in the non-pi case) -- thus
10 * mimicking a regular futex_wait.
11 */
12
13/* For the CLR_() macros */
14#include <string.h>
15#include <pthread.h>
16
17#include <signal.h>
18#include "../util/mutex.h"
19#include "../util/stat.h"
20#include <subcmd/parse-options.h>
21#include <linux/compiler.h>
22#include <linux/kernel.h>
23#include <linux/time64.h>
24#include <errno.h>
25#include <perf/cpumap.h>
26#include "bench.h"
27#include "futex.h"
28
29#include <err.h>
30#include <stdlib.h>
31#include <sys/time.h>
32#include <sys/mman.h>
33
34static u_int32_t futex1 = 0, futex2 = 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 requeuetime_stats, requeued_stats;
41static unsigned int threads_starting;
42static int futex_flag = 0;
43
44static struct bench_futex_parameters params = {
45 /*
46 * How many tasks to requeue at a time.
47 * Default to 1 in order to make the kernel work more.
48 */
49 .nrequeue = 1,
50};
51
52static const struct option options[] = {
53 OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
54 OPT_UINTEGER('q', "nrequeue", ¶ms.nrequeue, "Specify amount of threads to requeue 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 OPT_BOOLEAN( 'B', "broadcast", ¶ms.broadcast, "Requeue all threads at once"),
59 OPT_BOOLEAN( 'p', "pi", ¶ms.pi, "Use PI-aware variants of FUTEX_CMP_REQUEUE"),
60
61 OPT_END()
62};
63
64static const char * const bench_futex_requeue_usage[] = {
65 "perf bench futex requeue <options>",
66 NULL
67};
68
69static void print_summary(void)
70{
71 double requeuetime_avg = avg_stats(&requeuetime_stats);
72 double requeuetime_stddev = stddev_stats(&requeuetime_stats);
73 unsigned int requeued_avg = avg_stats(&requeued_stats);
74
75 printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n",
76 requeued_avg,
77 params.nthreads,
78 requeuetime_avg / USEC_PER_MSEC,
79 rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
80}
81
82static void *workerfn(void *arg __maybe_unused)
83{
84 int ret;
85
86 mutex_lock(&thread_lock);
87 threads_starting--;
88 if (!threads_starting)
89 cond_signal(&thread_parent);
90 cond_wait(&thread_worker, &thread_lock);
91 mutex_unlock(&thread_lock);
92
93 while (1) {
94 if (!params.pi) {
95 ret = futex_wait(&futex1, 0, NULL, futex_flag);
96 if (!ret)
97 break;
98
99 if (ret && errno != EAGAIN) {
100 if (!params.silent)
101 warnx("futex_wait");
102 break;
103 }
104 } else {
105 ret = futex_wait_requeue_pi(&futex1, 0, &futex2,
106 NULL, futex_flag);
107 if (!ret) {
108 /* got the lock at futex2 */
109 futex_unlock_pi(&futex2, futex_flag);
110 break;
111 }
112
113 if (ret && errno != EAGAIN) {
114 if (!params.silent)
115 warnx("futex_wait_requeue_pi");
116 break;
117 }
118 }
119 }
120
121 return NULL;
122}
123
124static void block_threads(pthread_t *w, struct perf_cpu_map *cpu)
125{
126 cpu_set_t *cpuset;
127 unsigned int i;
128 int nrcpus = cpu__max_cpu().cpu;
129 size_t size;
130
131 threads_starting = params.nthreads;
132
133 cpuset = CPU_ALLOC(nrcpus);
134 BUG_ON(!cpuset);
135 size = CPU_ALLOC_SIZE(nrcpus);
136
137 /* create and block all threads */
138 for (i = 0; i < params.nthreads; i++) {
139 pthread_attr_t thread_attr;
140
141 pthread_attr_init(&thread_attr);
142 CPU_ZERO_S(size, cpuset);
143 CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset);
144
145 if (pthread_attr_setaffinity_np(&thread_attr, size, cpuset)) {
146 CPU_FREE(cpuset);
147 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
148 }
149
150 if (pthread_create(&w[i], &thread_attr, workerfn, NULL)) {
151 CPU_FREE(cpuset);
152 err(EXIT_FAILURE, "pthread_create");
153 }
154 pthread_attr_destroy(&thread_attr);
155 }
156 CPU_FREE(cpuset);
157}
158
159static void toggle_done(int sig __maybe_unused,
160 siginfo_t *info __maybe_unused,
161 void *uc __maybe_unused)
162{
163 done = true;
164}
165
166int bench_futex_requeue(int argc, const char **argv)
167{
168 int ret = 0;
169 unsigned int i, j;
170 struct sigaction act;
171 struct perf_cpu_map *cpu;
172
173 argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0);
174 if (argc)
175 goto err;
176
177 cpu = perf_cpu_map__new_online_cpus();
178 if (!cpu)
179 err(EXIT_FAILURE, "cpu_map__new");
180
181 memset(&act, 0, sizeof(act));
182 sigfillset(&act.sa_mask);
183 act.sa_sigaction = toggle_done;
184 sigaction(SIGINT, &act, NULL);
185
186 if (params.mlockall) {
187 if (mlockall(MCL_CURRENT | MCL_FUTURE))
188 err(EXIT_FAILURE, "mlockall");
189 }
190
191 if (!params.nthreads)
192 params.nthreads = perf_cpu_map__nr(cpu);
193
194 worker = calloc(params.nthreads, sizeof(*worker));
195 if (!worker)
196 err(EXIT_FAILURE, "calloc");
197
198 if (!params.fshared)
199 futex_flag = FUTEX_PRIVATE_FLAG;
200
201 if (params.nrequeue > params.nthreads)
202 params.nrequeue = params.nthreads;
203
204 if (params.broadcast)
205 params.nrequeue = params.nthreads;
206
207 printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %s%p), "
208 "%d at a time.\n\n", getpid(), params.nthreads,
209 params.fshared ? "shared":"private", &futex1,
210 params.pi ? "PI ": "", &futex2, params.nrequeue);
211
212 init_stats(&requeued_stats);
213 init_stats(&requeuetime_stats);
214 mutex_init(&thread_lock);
215 cond_init(&thread_parent);
216 cond_init(&thread_worker);
217
218 for (j = 0; j < bench_repeat && !done; j++) {
219 unsigned int nrequeued = 0, wakeups = 0;
220 struct timeval start, end, runtime;
221
222 /* create, launch & block all threads */
223 block_threads(worker, cpu);
224
225 /* make sure all threads are already blocked */
226 mutex_lock(&thread_lock);
227 while (threads_starting)
228 cond_wait(&thread_parent, &thread_lock);
229 cond_broadcast(&thread_worker);
230 mutex_unlock(&thread_lock);
231
232 usleep(100000);
233
234 /* Ok, all threads are patiently blocked, start requeueing */
235 gettimeofday(&start, NULL);
236 while (nrequeued < params.nthreads) {
237 int r;
238
239 /*
240 * For the regular non-pi case, do not wakeup any tasks
241 * blocked on futex1, allowing us to really measure
242 * futex_wait functionality. For the PI case the first
243 * waiter is always awoken.
244 */
245 if (!params.pi) {
246 r = futex_cmp_requeue(&futex1, 0, &futex2, 0,
247 params.nrequeue,
248 futex_flag);
249 } else {
250 r = futex_cmp_requeue_pi(&futex1, 0, &futex2,
251 params.nrequeue,
252 futex_flag);
253 wakeups++; /* assume no error */
254 }
255
256 if (r < 0)
257 err(EXIT_FAILURE, "couldn't requeue from %p to %p",
258 &futex1, &futex2);
259
260 nrequeued += r;
261 }
262
263 gettimeofday(&end, NULL);
264 timersub(&end, &start, &runtime);
265
266 update_stats(&requeued_stats, nrequeued);
267 update_stats(&requeuetime_stats, runtime.tv_usec);
268
269 if (!params.silent) {
270 if (!params.pi)
271 printf("[Run %d]: Requeued %d of %d threads in "
272 "%.4f ms\n", j + 1, nrequeued,
273 params.nthreads,
274 runtime.tv_usec / (double)USEC_PER_MSEC);
275 else {
276 nrequeued -= wakeups;
277 printf("[Run %d]: Awoke and Requeued (%d+%d) of "
278 "%d threads in %.4f ms\n",
279 j + 1, wakeups, nrequeued,
280 params.nthreads,
281 runtime.tv_usec / (double)USEC_PER_MSEC);
282 }
283
284 }
285
286 if (!params.pi) {
287 /* everybody should be blocked on futex2, wake'em up */
288 nrequeued = futex_wake(&futex2, nrequeued, futex_flag);
289 if (params.nthreads != nrequeued)
290 warnx("couldn't wakeup all tasks (%d/%d)",
291 nrequeued, params.nthreads);
292 }
293
294 for (i = 0; i < params.nthreads; i++) {
295 ret = pthread_join(worker[i], NULL);
296 if (ret)
297 err(EXIT_FAILURE, "pthread_join");
298 }
299 }
300
301 /* cleanup & report results */
302 cond_destroy(&thread_parent);
303 cond_destroy(&thread_worker);
304 mutex_destroy(&thread_lock);
305
306 print_summary();
307
308 free(worker);
309 perf_cpu_map__put(cpu);
310 return ret;
311err:
312 usage_with_options(bench_futex_requeue_usage, options);
313 exit(EXIT_FAILURE);
314}