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a0439711 DB |
1 | /* |
2 | * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com> | |
3 | * | |
4 | * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing. | |
5 | * | |
6 | * This program is particularly useful for measuring the kernel's futex hash | |
7 | * table/function implementation. In order for it to make sense, use with as | |
8 | * many threads and futexes as possible. | |
9 | */ | |
10 | ||
11 | #include "../perf.h" | |
12 | #include "../util/util.h" | |
13 | #include "../util/stat.h" | |
14 | #include "../util/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 | ||
24 | static unsigned int nthreads = 0; | |
25 | static unsigned int nsecs = 10; | |
26 | /* amount of futexes per thread */ | |
27 | static unsigned int nfutexes = 1024; | |
28 | static bool fshared = false, done = false, silent = false; | |
29 | ||
30 | struct timeval start, end, runtime; | |
31 | static pthread_mutex_t thread_lock; | |
32 | static unsigned int threads_starting; | |
33 | static struct stats throughput_stats; | |
34 | static pthread_cond_t thread_parent, thread_worker; | |
35 | ||
36 | struct worker { | |
37 | int tid; | |
38 | u_int32_t *futex; | |
39 | pthread_t thread; | |
40 | unsigned long ops; | |
41 | }; | |
42 | ||
43 | static const struct option options[] = { | |
44 | OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"), | |
45 | OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"), | |
46 | OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"), | |
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 | ||
52 | static const char * const bench_futex_hash_usage[] = { | |
53 | "perf bench futex hash <options>", | |
54 | NULL | |
55 | }; | |
56 | ||
57 | static void *workerfn(void *arg) | |
58 | { | |
59 | int ret; | |
60 | unsigned int i; | |
61 | struct worker *w = (struct worker *) arg; | |
62 | ||
63 | pthread_mutex_lock(&thread_lock); | |
64 | threads_starting--; | |
65 | if (!threads_starting) | |
66 | pthread_cond_signal(&thread_parent); | |
67 | pthread_cond_wait(&thread_worker, &thread_lock); | |
68 | pthread_mutex_unlock(&thread_lock); | |
69 | ||
70 | do { | |
71 | for (i = 0; i < nfutexes; i++, w->ops++) { | |
72 | /* | |
73 | * We want the futex calls to fail in order to stress | |
74 | * the hashing of uaddr and not measure other steps, | |
75 | * such as internal waitqueue handling, thus enlarging | |
76 | * the critical region protected by hb->lock. | |
77 | */ | |
78 | ret = futex_wait(&w->futex[i], 1234, NULL, | |
79 | fshared ? 0 : FUTEX_PRIVATE_FLAG); | |
80 | if (!silent && | |
81 | (!ret || errno != EAGAIN || errno != EWOULDBLOCK)) | |
82 | warn("Non-expected futex return call"); | |
83 | } | |
84 | } while (!done); | |
85 | ||
86 | return NULL; | |
87 | } | |
88 | ||
89 | static void toggle_done(int sig __maybe_unused, | |
90 | siginfo_t *info __maybe_unused, | |
91 | void *uc __maybe_unused) | |
92 | { | |
93 | /* inform all threads that we're done for the day */ | |
94 | done = true; | |
95 | gettimeofday(&end, NULL); | |
96 | timersub(&end, &start, &runtime); | |
97 | } | |
98 | ||
99 | static void print_summary(void) | |
100 | { | |
101 | unsigned long avg = avg_stats(&throughput_stats); | |
102 | double stddev = stddev_stats(&throughput_stats); | |
103 | ||
104 | printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", | |
105 | !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), | |
106 | (int) runtime.tv_sec); | |
107 | } | |
108 | ||
109 | int bench_futex_hash(int argc, const char **argv, | |
110 | const char *prefix __maybe_unused) | |
111 | { | |
112 | int ret = 0; | |
113 | cpu_set_t cpu; | |
114 | struct sigaction act; | |
115 | unsigned int i, ncpus; | |
116 | pthread_attr_t thread_attr; | |
117 | struct worker *worker = NULL; | |
118 | ||
119 | argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0); | |
120 | if (argc) { | |
121 | usage_with_options(bench_futex_hash_usage, options); | |
122 | exit(EXIT_FAILURE); | |
123 | } | |
124 | ||
125 | ncpus = sysconf(_SC_NPROCESSORS_ONLN); | |
126 | ||
127 | sigfillset(&act.sa_mask); | |
128 | act.sa_sigaction = toggle_done; | |
129 | sigaction(SIGINT, &act, NULL); | |
130 | ||
131 | if (!nthreads) /* default to the number of CPUs */ | |
132 | nthreads = ncpus; | |
133 | ||
134 | worker = calloc(nthreads, sizeof(*worker)); | |
135 | if (!worker) | |
136 | goto errmem; | |
137 | ||
138 | printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", | |
139 | getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs); | |
140 | ||
141 | init_stats(&throughput_stats); | |
142 | pthread_mutex_init(&thread_lock, NULL); | |
143 | pthread_cond_init(&thread_parent, NULL); | |
144 | pthread_cond_init(&thread_worker, NULL); | |
145 | ||
146 | threads_starting = nthreads; | |
147 | pthread_attr_init(&thread_attr); | |
148 | gettimeofday(&start, NULL); | |
149 | for (i = 0; i < nthreads; i++) { | |
150 | worker[i].tid = i; | |
151 | worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex)); | |
152 | if (!worker[i].futex) | |
153 | goto errmem; | |
154 | ||
155 | CPU_ZERO(&cpu); | |
156 | CPU_SET(i % ncpus, &cpu); | |
157 | ||
158 | ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu); | |
159 | if (ret) | |
160 | err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); | |
161 | ||
162 | ret = pthread_create(&worker[i].thread, &thread_attr, workerfn, | |
163 | (void *)(struct worker *) &worker[i]); | |
164 | if (ret) | |
165 | err(EXIT_FAILURE, "pthread_create"); | |
166 | ||
167 | } | |
168 | pthread_attr_destroy(&thread_attr); | |
169 | ||
170 | pthread_mutex_lock(&thread_lock); | |
171 | while (threads_starting) | |
172 | pthread_cond_wait(&thread_parent, &thread_lock); | |
173 | pthread_cond_broadcast(&thread_worker); | |
174 | pthread_mutex_unlock(&thread_lock); | |
175 | ||
176 | sleep(nsecs); | |
177 | toggle_done(0, NULL, NULL); | |
178 | ||
179 | for (i = 0; i < nthreads; i++) { | |
180 | ret = pthread_join(worker[i].thread, NULL); | |
181 | if (ret) | |
182 | err(EXIT_FAILURE, "pthread_join"); | |
183 | } | |
184 | ||
185 | /* cleanup & report results */ | |
186 | pthread_cond_destroy(&thread_parent); | |
187 | pthread_cond_destroy(&thread_worker); | |
188 | pthread_mutex_destroy(&thread_lock); | |
189 | ||
190 | for (i = 0; i < nthreads; i++) { | |
191 | unsigned long t = worker[i].ops/runtime.tv_sec; | |
192 | update_stats(&throughput_stats, t); | |
193 | if (!silent) { | |
194 | if (nfutexes == 1) | |
195 | printf("[thread %2d] futex: %p [ %ld ops/sec ]\n", | |
196 | worker[i].tid, &worker[i].futex[0], t); | |
197 | else | |
198 | printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n", | |
199 | worker[i].tid, &worker[i].futex[0], | |
200 | &worker[i].futex[nfutexes-1], t); | |
201 | } | |
202 | ||
203 | free(worker[i].futex); | |
204 | } | |
205 | ||
206 | print_summary(); | |
207 | ||
208 | free(worker); | |
209 | return ret; | |
210 | errmem: | |
211 | err(EXIT_FAILURE, "calloc"); | |
212 | } |