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0fb298cf DB |
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" | |
4b6ab94e | 14 | #include <subcmd/parse-options.h> |
0fb298cf DB |
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 | static 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 | */ | |
30 | static unsigned int nrequeue = 1; | |
31 | ||
0fb298cf | 32 | static pthread_t *worker; |
86c87e13 | 33 | static bool done = false, silent = false, fshared = false; |
0fb298cf DB |
34 | static pthread_mutex_t thread_lock; |
35 | static pthread_cond_t thread_parent, thread_worker; | |
36 | static struct stats requeuetime_stats, requeued_stats; | |
37 | static unsigned int ncpus, threads_starting, nthreads = 0; | |
86c87e13 | 38 | static int futex_flag = 0; |
0fb298cf DB |
39 | |
40 | static 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"), | |
0fb298cf | 43 | OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"), |
86c87e13 | 44 | OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"), |
0fb298cf DB |
45 | OPT_END() |
46 | }; | |
47 | ||
48 | static const char * const bench_futex_requeue_usage[] = { | |
49 | "perf bench futex requeue <options>", | |
50 | NULL | |
51 | }; | |
52 | ||
53 | static 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 | ||
66 | static 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 | ||
86c87e13 | 75 | futex_wait(&futex1, 0, NULL, futex_flag); |
0fb298cf DB |
76 | return NULL; |
77 | } | |
78 | ||
79 | static 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 | ||
100 | static void toggle_done(int sig __maybe_unused, | |
101 | siginfo_t *info __maybe_unused, | |
102 | void *uc __maybe_unused) | |
103 | { | |
104 | done = true; | |
105 | } | |
106 | ||
107 | int 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 | ||
86c87e13 DB |
132 | if (!fshared) |
133 | futex_flag = FUTEX_PRIVATE_FLAG; | |
134 | ||
052b0f6e DB |
135 | if (nrequeue > nthreads) |
136 | nrequeue = nthreads; | |
137 | ||
86c87e13 DB |
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); | |
0fb298cf DB |
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 | ||
d9de84af | 149 | for (j = 0; j < bench_repeat && !done; j++) { |
0fb298cf DB |
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); | |
052b0f6e | 167 | while (nrequeued < nthreads) { |
0fb298cf DB |
168 | /* |
169 | * Do not wakeup any tasks blocked on futex1, allowing | |
170 | * us to really measure futex_wait functionality. | |
171 | */ | |
052b0f6e DB |
172 | nrequeued += futex_cmp_requeue(&futex1, 0, &futex2, 0, |
173 | nrequeue, futex_flag); | |
86c87e13 | 174 | } |
052b0f6e | 175 | |
0fb298cf DB |
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 */ | |
052b0f6e | 188 | nrequeued = futex_wake(&futex2, nrequeued, futex_flag); |
0fb298cf DB |
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 | } | |
0fb298cf DB |
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; | |
209 | err: | |
210 | usage_with_options(bench_futex_requeue_usage, options); | |
211 | exit(EXIT_FAILURE); | |
212 | } |