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d65817b4 DB |
1 | /* |
2 | * Copyright (C) 2015 Davidlohr Bueso. | |
3 | * | |
4 | * Block a bunch of threads and let parallel waker threads wakeup an | |
5 | * equal amount of them. The program output reflects the avg latency | |
6 | * for each individual thread to service its share of work. Ultimately | |
7 | * it can be used to measure futex_wake() changes. | |
8 | */ | |
9 | ||
8a158589 ACM |
10 | /* For the CLR_() macros */ |
11 | #include <pthread.h> | |
12 | ||
9c304f6c | 13 | #include <signal.h> |
d65817b4 | 14 | #include "../util/stat.h" |
4b6ab94e | 15 | #include <subcmd/parse-options.h> |
86695f59 | 16 | #include <linux/compiler.h> |
9c304f6c | 17 | #include <linux/kernel.h> |
565e6911 | 18 | #include <linux/time64.h> |
9c304f6c | 19 | #include <errno.h> |
d65817b4 DB |
20 | #include "bench.h" |
21 | #include "futex.h" | |
22 | ||
23 | #include <err.h> | |
24 | #include <stdlib.h> | |
25 | #include <sys/time.h> | |
d65817b4 DB |
26 | |
27 | struct thread_data { | |
28 | pthread_t worker; | |
29 | unsigned int nwoken; | |
30 | struct timeval runtime; | |
31 | }; | |
32 | ||
33 | static unsigned int nwakes = 1; | |
34 | ||
35 | /* all threads will block on the same futex -- hash bucket chaos ;) */ | |
36 | static u_int32_t futex = 0; | |
37 | ||
38 | static pthread_t *blocked_worker; | |
39 | static bool done = false, silent = false, fshared = false; | |
40 | static unsigned int nblocked_threads = 0, nwaking_threads = 0; | |
41 | static pthread_mutex_t thread_lock; | |
42 | static pthread_cond_t thread_parent, thread_worker; | |
43 | static struct stats waketime_stats, wakeup_stats; | |
44 | static unsigned int ncpus, threads_starting; | |
45 | static int futex_flag = 0; | |
46 | ||
47 | static const struct option options[] = { | |
48 | OPT_UINTEGER('t', "threads", &nblocked_threads, "Specify amount of threads"), | |
49 | OPT_UINTEGER('w', "nwakers", &nwaking_threads, "Specify amount of waking threads"), | |
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 | ||
55 | static const char * const bench_futex_wake_parallel_usage[] = { | |
56 | "perf bench futex wake-parallel <options>", | |
57 | NULL | |
58 | }; | |
59 | ||
60 | static void *waking_workerfn(void *arg) | |
61 | { | |
62 | struct thread_data *waker = (struct thread_data *) arg; | |
63 | struct timeval start, end; | |
64 | ||
65 | gettimeofday(&start, NULL); | |
66 | ||
67 | waker->nwoken = futex_wake(&futex, nwakes, futex_flag); | |
68 | if (waker->nwoken != nwakes) | |
69 | warnx("couldn't wakeup all tasks (%d/%d)", | |
70 | waker->nwoken, nwakes); | |
71 | ||
72 | gettimeofday(&end, NULL); | |
73 | timersub(&end, &start, &waker->runtime); | |
74 | ||
75 | pthread_exit(NULL); | |
76 | return NULL; | |
77 | } | |
78 | ||
79 | static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr) | |
80 | { | |
81 | unsigned int i; | |
82 | ||
83 | pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE); | |
84 | ||
85 | /* create and block all threads */ | |
86 | for (i = 0; i < nwaking_threads; i++) { | |
87 | /* | |
88 | * Thread creation order will impact per-thread latency | |
89 | * as it will affect the order to acquire the hb spinlock. | |
90 | * For now let the scheduler decide. | |
91 | */ | |
92 | if (pthread_create(&td[i].worker, &thread_attr, | |
93 | waking_workerfn, (void *)&td[i])) | |
94 | err(EXIT_FAILURE, "pthread_create"); | |
95 | } | |
96 | ||
97 | for (i = 0; i < nwaking_threads; i++) | |
98 | if (pthread_join(td[i].worker, NULL)) | |
99 | err(EXIT_FAILURE, "pthread_join"); | |
100 | } | |
101 | ||
102 | static void *blocked_workerfn(void *arg __maybe_unused) | |
103 | { | |
104 | pthread_mutex_lock(&thread_lock); | |
105 | threads_starting--; | |
106 | if (!threads_starting) | |
107 | pthread_cond_signal(&thread_parent); | |
108 | pthread_cond_wait(&thread_worker, &thread_lock); | |
109 | pthread_mutex_unlock(&thread_lock); | |
110 | ||
111 | while (1) { /* handle spurious wakeups */ | |
112 | if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR) | |
113 | break; | |
114 | } | |
115 | ||
116 | pthread_exit(NULL); | |
117 | return NULL; | |
118 | } | |
119 | ||
120 | static void block_threads(pthread_t *w, pthread_attr_t thread_attr) | |
121 | { | |
122 | cpu_set_t cpu; | |
123 | unsigned int i; | |
124 | ||
125 | threads_starting = nblocked_threads; | |
126 | ||
127 | /* create and block all threads */ | |
128 | for (i = 0; i < nblocked_threads; i++) { | |
129 | CPU_ZERO(&cpu); | |
130 | CPU_SET(i % ncpus, &cpu); | |
131 | ||
132 | if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu)) | |
133 | err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); | |
134 | ||
135 | if (pthread_create(&w[i], &thread_attr, blocked_workerfn, NULL)) | |
136 | err(EXIT_FAILURE, "pthread_create"); | |
137 | } | |
138 | } | |
139 | ||
140 | static void print_run(struct thread_data *waking_worker, unsigned int run_num) | |
141 | { | |
142 | unsigned int i, wakeup_avg; | |
143 | double waketime_avg, waketime_stddev; | |
144 | struct stats __waketime_stats, __wakeup_stats; | |
145 | ||
146 | init_stats(&__wakeup_stats); | |
147 | init_stats(&__waketime_stats); | |
148 | ||
149 | for (i = 0; i < nwaking_threads; i++) { | |
150 | update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec); | |
151 | update_stats(&__wakeup_stats, waking_worker[i].nwoken); | |
152 | } | |
153 | ||
154 | waketime_avg = avg_stats(&__waketime_stats); | |
155 | waketime_stddev = stddev_stats(&__waketime_stats); | |
156 | wakeup_avg = avg_stats(&__wakeup_stats); | |
157 | ||
158 | printf("[Run %d]: Avg per-thread latency (waking %d/%d threads) " | |
159 | "in %.4f ms (+-%.2f%%)\n", run_num + 1, wakeup_avg, | |
565e6911 | 160 | nblocked_threads, waketime_avg / USEC_PER_MSEC, |
d65817b4 DB |
161 | rel_stddev_stats(waketime_stddev, waketime_avg)); |
162 | } | |
163 | ||
164 | static void print_summary(void) | |
165 | { | |
166 | unsigned int wakeup_avg; | |
167 | double waketime_avg, waketime_stddev; | |
168 | ||
169 | waketime_avg = avg_stats(&waketime_stats); | |
170 | waketime_stddev = stddev_stats(&waketime_stats); | |
171 | wakeup_avg = avg_stats(&wakeup_stats); | |
172 | ||
173 | printf("Avg per-thread latency (waking %d/%d threads) in %.4f ms (+-%.2f%%)\n", | |
174 | wakeup_avg, | |
175 | nblocked_threads, | |
565e6911 | 176 | waketime_avg / USEC_PER_MSEC, |
d65817b4 DB |
177 | rel_stddev_stats(waketime_stddev, waketime_avg)); |
178 | } | |
179 | ||
180 | ||
181 | static void do_run_stats(struct thread_data *waking_worker) | |
182 | { | |
183 | unsigned int i; | |
184 | ||
185 | for (i = 0; i < nwaking_threads; i++) { | |
186 | update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec); | |
187 | update_stats(&wakeup_stats, waking_worker[i].nwoken); | |
188 | } | |
189 | ||
190 | } | |
191 | ||
192 | static void toggle_done(int sig __maybe_unused, | |
193 | siginfo_t *info __maybe_unused, | |
194 | void *uc __maybe_unused) | |
195 | { | |
196 | done = true; | |
197 | } | |
198 | ||
199 | int bench_futex_wake_parallel(int argc, const char **argv, | |
200 | const char *prefix __maybe_unused) | |
201 | { | |
202 | int ret = 0; | |
203 | unsigned int i, j; | |
204 | struct sigaction act; | |
205 | pthread_attr_t thread_attr; | |
206 | struct thread_data *waking_worker; | |
207 | ||
208 | argc = parse_options(argc, argv, options, | |
209 | bench_futex_wake_parallel_usage, 0); | |
210 | if (argc) { | |
211 | usage_with_options(bench_futex_wake_parallel_usage, options); | |
212 | exit(EXIT_FAILURE); | |
213 | } | |
214 | ||
215 | sigfillset(&act.sa_mask); | |
216 | act.sa_sigaction = toggle_done; | |
217 | sigaction(SIGINT, &act, NULL); | |
218 | ||
219 | ncpus = sysconf(_SC_NPROCESSORS_ONLN); | |
220 | if (!nblocked_threads) | |
221 | nblocked_threads = ncpus; | |
222 | ||
223 | /* some sanity checks */ | |
224 | if (nwaking_threads > nblocked_threads || !nwaking_threads) | |
225 | nwaking_threads = nblocked_threads; | |
226 | ||
227 | if (nblocked_threads % nwaking_threads) | |
228 | errx(EXIT_FAILURE, "Must be perfectly divisible"); | |
229 | /* | |
230 | * Each thread will wakeup nwakes tasks in | |
231 | * a single futex_wait call. | |
232 | */ | |
233 | nwakes = nblocked_threads/nwaking_threads; | |
234 | ||
235 | blocked_worker = calloc(nblocked_threads, sizeof(*blocked_worker)); | |
236 | if (!blocked_worker) | |
237 | err(EXIT_FAILURE, "calloc"); | |
238 | ||
239 | if (!fshared) | |
240 | futex_flag = FUTEX_PRIVATE_FLAG; | |
241 | ||
242 | printf("Run summary [PID %d]: blocking on %d threads (at [%s] " | |
243 | "futex %p), %d threads waking up %d at a time.\n\n", | |
244 | getpid(), nblocked_threads, fshared ? "shared":"private", | |
245 | &futex, nwaking_threads, nwakes); | |
246 | ||
247 | init_stats(&wakeup_stats); | |
248 | init_stats(&waketime_stats); | |
249 | ||
250 | pthread_attr_init(&thread_attr); | |
251 | pthread_mutex_init(&thread_lock, NULL); | |
252 | pthread_cond_init(&thread_parent, NULL); | |
253 | pthread_cond_init(&thread_worker, NULL); | |
254 | ||
255 | for (j = 0; j < bench_repeat && !done; j++) { | |
256 | waking_worker = calloc(nwaking_threads, sizeof(*waking_worker)); | |
257 | if (!waking_worker) | |
258 | err(EXIT_FAILURE, "calloc"); | |
259 | ||
260 | /* create, launch & block all threads */ | |
261 | block_threads(blocked_worker, thread_attr); | |
262 | ||
263 | /* make sure all threads are already blocked */ | |
264 | pthread_mutex_lock(&thread_lock); | |
265 | while (threads_starting) | |
266 | pthread_cond_wait(&thread_parent, &thread_lock); | |
267 | pthread_cond_broadcast(&thread_worker); | |
268 | pthread_mutex_unlock(&thread_lock); | |
269 | ||
270 | usleep(100000); | |
271 | ||
272 | /* Ok, all threads are patiently blocked, start waking folks up */ | |
273 | wakeup_threads(waking_worker, thread_attr); | |
274 | ||
275 | for (i = 0; i < nblocked_threads; i++) { | |
276 | ret = pthread_join(blocked_worker[i], NULL); | |
277 | if (ret) | |
278 | err(EXIT_FAILURE, "pthread_join"); | |
279 | } | |
280 | ||
281 | do_run_stats(waking_worker); | |
282 | if (!silent) | |
283 | print_run(waking_worker, j); | |
284 | ||
285 | free(waking_worker); | |
286 | } | |
287 | ||
288 | /* cleanup & report results */ | |
289 | pthread_cond_destroy(&thread_parent); | |
290 | pthread_cond_destroy(&thread_worker); | |
291 | pthread_mutex_destroy(&thread_lock); | |
292 | pthread_attr_destroy(&thread_attr); | |
293 | ||
294 | print_summary(); | |
295 | ||
296 | free(blocked_worker); | |
297 | return ret; | |
298 | } |