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-rw-r--r--tools/perf/bench/futex-hash.c212
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diff --git a/tools/perf/bench/futex-hash.c b/tools/perf/bench/futex-hash.c
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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
24static unsigned int nthreads = 0;
25static unsigned int nsecs = 10;
26/* amount of futexes per thread */
27static unsigned int nfutexes = 1024;
28static bool fshared = false, done = false, silent = false;
29
30struct timeval start, end, runtime;
31static pthread_mutex_t thread_lock;
32static unsigned int threads_starting;
33static struct stats throughput_stats;
34static pthread_cond_t thread_parent, thread_worker;
35
36struct worker {
37 int tid;
38 u_int32_t *futex;
39 pthread_t thread;
40 unsigned long ops;
41};
42
43static 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
52static const char * const bench_futex_hash_usage[] = {
53 "perf bench futex hash <options>",
54 NULL
55};
56
57static 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
89static 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
99static 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
109int 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;
210errmem:
211 err(EXIT_FAILURE, "calloc");
212}
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