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1/*
2 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
3 *
4 * futex-requeue: Block a bunch of threads on futex1 and requeue them
5 * on futex2, N at a time.
6 *
7 * This program is particularly useful to measure the latency of nthread
8 * requeues without waking up any tasks -- thus mimicking a regular futex_wait.
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
24static u_int32_t futex1 = 0, futex2 = 0;
25
26/*
27 * How many tasks to requeue at a time.
28 * Default to 1 in order to make the kernel work more.
29 */
30static unsigned int nrequeue = 1;
31
32static pthread_t *worker;
33static bool done = false, silent = false, fshared = false;
34static pthread_mutex_t thread_lock;
35static pthread_cond_t thread_parent, thread_worker;
36static struct stats requeuetime_stats, requeued_stats;
37static unsigned int ncpus, threads_starting, nthreads = 0;
38static int futex_flag = 0;
39
40static const struct option options[] = {
41 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
42 OPT_UINTEGER('q', "nrequeue", &nrequeue, "Specify amount of threads to requeue at once"),
43 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
44 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
45 OPT_END()
46};
47
48static const char * const bench_futex_requeue_usage[] = {
49 "perf bench futex requeue <options>",
50 NULL
51};
52
53static void print_summary(void)
54{
55 double requeuetime_avg = avg_stats(&requeuetime_stats);
56 double requeuetime_stddev = stddev_stats(&requeuetime_stats);
57 unsigned int requeued_avg = avg_stats(&requeued_stats);
58
59 printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n",
60 requeued_avg,
61 nthreads,
62 requeuetime_avg/1e3,
63 rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
64}
65
66static void *workerfn(void *arg __maybe_unused)
67{
68 pthread_mutex_lock(&thread_lock);
69 threads_starting--;
70 if (!threads_starting)
71 pthread_cond_signal(&thread_parent);
72 pthread_cond_wait(&thread_worker, &thread_lock);
73 pthread_mutex_unlock(&thread_lock);
74
75 futex_wait(&futex1, 0, NULL, futex_flag);
76 return NULL;
77}
78
79static void block_threads(pthread_t *w,
80 pthread_attr_t thread_attr)
81{
82 cpu_set_t cpu;
83 unsigned int i;
84
85 threads_starting = nthreads;
86
87 /* create and block all threads */
88 for (i = 0; i < nthreads; i++) {
89 CPU_ZERO(&cpu);
90 CPU_SET(i % ncpus, &cpu);
91
92 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
93 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
94
95 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
96 err(EXIT_FAILURE, "pthread_create");
97 }
98}
99
100static void toggle_done(int sig __maybe_unused,
101 siginfo_t *info __maybe_unused,
102 void *uc __maybe_unused)
103{
104 done = true;
105}
106
107int bench_futex_requeue(int argc, const char **argv,
108 const char *prefix __maybe_unused)
109{
110 int ret = 0;
111 unsigned int i, j;
112 struct sigaction act;
113 pthread_attr_t thread_attr;
114
115 argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0);
116 if (argc)
117 goto err;
118
119 ncpus = sysconf(_SC_NPROCESSORS_ONLN);
120
121 sigfillset(&act.sa_mask);
122 act.sa_sigaction = toggle_done;
123 sigaction(SIGINT, &act, NULL);
124
125 if (!nthreads)
126 nthreads = ncpus;
127
128 worker = calloc(nthreads, sizeof(*worker));
129 if (!worker)
130 err(EXIT_FAILURE, "calloc");
131
132 if (!fshared)
133 futex_flag = FUTEX_PRIVATE_FLAG;
134
135 if (nrequeue > nthreads)
136 nrequeue = nthreads;
137
138 printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %p), "
139 "%d at a time.\n\n", getpid(), nthreads,
140 fshared ? "shared":"private", &futex1, &futex2, nrequeue);
141
142 init_stats(&requeued_stats);
143 init_stats(&requeuetime_stats);
144 pthread_attr_init(&thread_attr);
145 pthread_mutex_init(&thread_lock, NULL);
146 pthread_cond_init(&thread_parent, NULL);
147 pthread_cond_init(&thread_worker, NULL);
148
149 for (j = 0; j < bench_repeat && !done; j++) {
150 unsigned int nrequeued = 0;
151 struct timeval start, end, runtime;
152
153 /* create, launch & block all threads */
154 block_threads(worker, thread_attr);
155
156 /* make sure all threads are already blocked */
157 pthread_mutex_lock(&thread_lock);
158 while (threads_starting)
159 pthread_cond_wait(&thread_parent, &thread_lock);
160 pthread_cond_broadcast(&thread_worker);
161 pthread_mutex_unlock(&thread_lock);
162
163 usleep(100000);
164
165 /* Ok, all threads are patiently blocked, start requeueing */
166 gettimeofday(&start, NULL);
167 while (nrequeued < nthreads) {
168 /*
169 * Do not wakeup any tasks blocked on futex1, allowing
170 * us to really measure futex_wait functionality.
171 */
172 nrequeued += futex_cmp_requeue(&futex1, 0, &futex2, 0,
173 nrequeue, futex_flag);
174 }
175
176 gettimeofday(&end, NULL);
177 timersub(&end, &start, &runtime);
178
179 update_stats(&requeued_stats, nrequeued);
180 update_stats(&requeuetime_stats, runtime.tv_usec);
181
182 if (!silent) {
183 printf("[Run %d]: Requeued %d of %d threads in %.4f ms\n",
184 j + 1, nrequeued, nthreads, runtime.tv_usec/1e3);
185 }
186
187 /* everybody should be blocked on futex2, wake'em up */
188 nrequeued = futex_wake(&futex2, nrequeued, futex_flag);
189 if (nthreads != nrequeued)
190 warnx("couldn't wakeup all tasks (%d/%d)", nrequeued, nthreads);
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 /* cleanup & report results */
200 pthread_cond_destroy(&thread_parent);
201 pthread_cond_destroy(&thread_worker);
202 pthread_mutex_destroy(&thread_lock);
203 pthread_attr_destroy(&thread_attr);
204
205 print_summary();
206
207 free(worker);
208 return ret;
209err:
210 usage_with_options(bench_futex_requeue_usage, options);
211 exit(EXIT_FAILURE);
212}
1/*
2 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
3 *
4 * futex-requeue: Block a bunch of threads on futex1 and requeue them
5 * on futex2, N at a time.
6 *
7 * This program is particularly useful to measure the latency of nthread
8 * requeues without waking up any tasks -- thus mimicking a regular futex_wait.
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
28static u_int32_t futex1 = 0, futex2 = 0;
29
30/*
31 * How many tasks to requeue at a time.
32 * Default to 1 in order to make the kernel work more.
33 */
34static unsigned int nrequeue = 1;
35
36static pthread_t *worker;
37static bool done = false, silent = false, fshared = false;
38static pthread_mutex_t thread_lock;
39static pthread_cond_t thread_parent, thread_worker;
40static struct stats requeuetime_stats, requeued_stats;
41static unsigned int ncpus, threads_starting, nthreads = 0;
42static int futex_flag = 0;
43
44static const struct option options[] = {
45 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
46 OPT_UINTEGER('q', "nrequeue", &nrequeue, "Specify amount of threads to requeue at once"),
47 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
48 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
49 OPT_END()
50};
51
52static const char * const bench_futex_requeue_usage[] = {
53 "perf bench futex requeue <options>",
54 NULL
55};
56
57static void print_summary(void)
58{
59 double requeuetime_avg = avg_stats(&requeuetime_stats);
60 double requeuetime_stddev = stddev_stats(&requeuetime_stats);
61 unsigned int requeued_avg = avg_stats(&requeued_stats);
62
63 printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n",
64 requeued_avg,
65 nthreads,
66 requeuetime_avg / USEC_PER_MSEC,
67 rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
68}
69
70static void *workerfn(void *arg __maybe_unused)
71{
72 pthread_mutex_lock(&thread_lock);
73 threads_starting--;
74 if (!threads_starting)
75 pthread_cond_signal(&thread_parent);
76 pthread_cond_wait(&thread_worker, &thread_lock);
77 pthread_mutex_unlock(&thread_lock);
78
79 futex_wait(&futex1, 0, NULL, futex_flag);
80 return NULL;
81}
82
83static void block_threads(pthread_t *w,
84 pthread_attr_t thread_attr)
85{
86 cpu_set_t cpu;
87 unsigned int i;
88
89 threads_starting = nthreads;
90
91 /* create and block all threads */
92 for (i = 0; i < nthreads; i++) {
93 CPU_ZERO(&cpu);
94 CPU_SET(i % ncpus, &cpu);
95
96 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
97 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
98
99 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
100 err(EXIT_FAILURE, "pthread_create");
101 }
102}
103
104static void toggle_done(int sig __maybe_unused,
105 siginfo_t *info __maybe_unused,
106 void *uc __maybe_unused)
107{
108 done = true;
109}
110
111int bench_futex_requeue(int argc, const char **argv,
112 const char *prefix __maybe_unused)
113{
114 int ret = 0;
115 unsigned int i, j;
116 struct sigaction act;
117 pthread_attr_t thread_attr;
118
119 argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0);
120 if (argc)
121 goto err;
122
123 ncpus = sysconf(_SC_NPROCESSORS_ONLN);
124
125 sigfillset(&act.sa_mask);
126 act.sa_sigaction = toggle_done;
127 sigaction(SIGINT, &act, NULL);
128
129 if (!nthreads)
130 nthreads = ncpus;
131 else
132 nthreads = futexbench_sanitize_numeric(nthreads);
133
134 worker = calloc(nthreads, sizeof(*worker));
135 if (!worker)
136 err(EXIT_FAILURE, "calloc");
137
138 if (!fshared)
139 futex_flag = FUTEX_PRIVATE_FLAG;
140
141 if (nrequeue > nthreads)
142 nrequeue = nthreads;
143
144 printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %p), "
145 "%d at a time.\n\n", getpid(), nthreads,
146 fshared ? "shared":"private", &futex1, &futex2, nrequeue);
147
148 init_stats(&requeued_stats);
149 init_stats(&requeuetime_stats);
150 pthread_attr_init(&thread_attr);
151 pthread_mutex_init(&thread_lock, NULL);
152 pthread_cond_init(&thread_parent, NULL);
153 pthread_cond_init(&thread_worker, NULL);
154
155 for (j = 0; j < bench_repeat && !done; j++) {
156 unsigned int nrequeued = 0;
157 struct timeval start, end, runtime;
158
159 /* create, launch & block all threads */
160 block_threads(worker, thread_attr);
161
162 /* make sure all threads are already blocked */
163 pthread_mutex_lock(&thread_lock);
164 while (threads_starting)
165 pthread_cond_wait(&thread_parent, &thread_lock);
166 pthread_cond_broadcast(&thread_worker);
167 pthread_mutex_unlock(&thread_lock);
168
169 usleep(100000);
170
171 /* Ok, all threads are patiently blocked, start requeueing */
172 gettimeofday(&start, NULL);
173 while (nrequeued < nthreads) {
174 /*
175 * Do not wakeup any tasks blocked on futex1, allowing
176 * us to really measure futex_wait functionality.
177 */
178 nrequeued += futex_cmp_requeue(&futex1, 0, &futex2, 0,
179 nrequeue, futex_flag);
180 }
181
182 gettimeofday(&end, NULL);
183 timersub(&end, &start, &runtime);
184
185 update_stats(&requeued_stats, nrequeued);
186 update_stats(&requeuetime_stats, runtime.tv_usec);
187
188 if (!silent) {
189 printf("[Run %d]: Requeued %d of %d threads in %.4f ms\n",
190 j + 1, nrequeued, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
191 }
192
193 /* everybody should be blocked on futex2, wake'em up */
194 nrequeued = futex_wake(&futex2, nrequeued, futex_flag);
195 if (nthreads != nrequeued)
196 warnx("couldn't wakeup all tasks (%d/%d)", nrequeued, nthreads);
197
198 for (i = 0; i < nthreads; i++) {
199 ret = pthread_join(worker[i], NULL);
200 if (ret)
201 err(EXIT_FAILURE, "pthread_join");
202 }
203 }
204
205 /* cleanup & report results */
206 pthread_cond_destroy(&thread_parent);
207 pthread_cond_destroy(&thread_worker);
208 pthread_mutex_destroy(&thread_lock);
209 pthread_attr_destroy(&thread_attr);
210
211 print_summary();
212
213 free(worker);
214 return ret;
215err:
216 usage_with_options(bench_futex_requeue_usage, options);
217 exit(EXIT_FAILURE);
218}