1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
4 *
5 * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
6 *
7 * This program is particularly useful for measuring the kernel's futex hash
8 * table/function implementation. In order for it to make sense, use with as
9 * many threads and futexes as possible.
10 */
11
12 /* For the CLR_() macros */
13 #include <string.h>
14 #include <pthread.h>
15
16 #include <errno.h>
17 #include <signal.h>
18 #include <stdlib.h>
19 #include <linux/compiler.h>
20 #include <linux/kernel.h>
21 #include <linux/zalloc.h>
22 #include <sys/time.h>
23 #include <sys/mman.h>
24 #include <perf/cpumap.h>
25
26 #include "../util/stat.h"
27 #include <subcmd/parse-options.h>
28 #include "bench.h"
29 #include "futex.h"
30
31 #include <err.h>
32
33 static bool done = false;
34 static int futex_flag = 0;
35
36 struct timeval bench__start, bench__end, bench__runtime;
37 static pthread_mutex_t thread_lock;
38 static unsigned int threads_starting;
39 static struct stats throughput_stats;
40 static pthread_cond_t thread_parent, thread_worker;
41
42 struct worker {
43 int tid;
44 u_int32_t *futex;
45 pthread_t thread;
46 unsigned long ops;
47 };
48
49 static struct bench_futex_parameters params = {
50 .nfutexes = 1024,
51 .runtime = 10,
52 };
53
54 static const struct option options[] = {
55 OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
56 OPT_UINTEGER('r', "runtime", ¶ms.runtime, "Specify runtime (in seconds)"),
57 OPT_UINTEGER('f', "futexes", ¶ms.nfutexes, "Specify amount of futexes per threads"),
58 OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"),
59 OPT_BOOLEAN( 'S', "shared", ¶ms.fshared, "Use shared futexes instead of private ones"),
60 OPT_BOOLEAN( 'm', "mlockall", ¶ms.mlockall, "Lock all current and future memory"),
61 OPT_END()
62 };
63
64 static const char * const bench_futex_hash_usage[] = {
65 "perf bench futex hash <options>",
66 NULL
67 };
68
workerfn(void * arg)69 static void *workerfn(void *arg)
70 {
71 int ret;
72 struct worker *w = (struct worker *) arg;
73 unsigned int i;
74 unsigned long ops = w->ops; /* avoid cacheline bouncing */
75
76 pthread_mutex_lock(&thread_lock);
77 threads_starting--;
78 if (!threads_starting)
79 pthread_cond_signal(&thread_parent);
80 pthread_cond_wait(&thread_worker, &thread_lock);
81 pthread_mutex_unlock(&thread_lock);
82
83 do {
84 for (i = 0; i < params.nfutexes; i++, ops++) {
85 /*
86 * We want the futex calls to fail in order to stress
87 * the hashing of uaddr and not measure other steps,
88 * such as internal waitqueue handling, thus enlarging
89 * the critical region protected by hb->lock.
90 */
91 ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag);
92 if (!params.silent &&
93 (!ret || errno != EAGAIN || errno != EWOULDBLOCK))
94 warn("Non-expected futex return call");
95 }
96 } while (!done);
97
98 w->ops = ops;
99 return NULL;
100 }
101
toggle_done(int sig __maybe_unused,siginfo_t * info __maybe_unused,void * uc __maybe_unused)102 static void toggle_done(int sig __maybe_unused,
103 siginfo_t *info __maybe_unused,
104 void *uc __maybe_unused)
105 {
106 /* inform all threads that we're done for the day */
107 done = true;
108 gettimeofday(&bench__end, NULL);
109 timersub(&bench__end, &bench__start, &bench__runtime);
110 }
111
print_summary(void)112 static void print_summary(void)
113 {
114 unsigned long avg = avg_stats(&throughput_stats);
115 double stddev = stddev_stats(&throughput_stats);
116
117 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
118 !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
119 (int)bench__runtime.tv_sec);
120 }
121
bench_futex_hash(int argc,const char ** argv)122 int bench_futex_hash(int argc, const char **argv)
123 {
124 int ret = 0;
125 cpu_set_t cpuset;
126 struct sigaction act;
127 unsigned int i;
128 pthread_attr_t thread_attr;
129 struct worker *worker = NULL;
130 struct perf_cpu_map *cpu;
131
132 argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0);
133 if (argc) {
134 usage_with_options(bench_futex_hash_usage, options);
135 exit(EXIT_FAILURE);
136 }
137
138 cpu = perf_cpu_map__new(NULL);
139 if (!cpu)
140 goto errmem;
141
142 memset(&act, 0, sizeof(act));
143 sigfillset(&act.sa_mask);
144 act.sa_sigaction = toggle_done;
145 sigaction(SIGINT, &act, NULL);
146
147 if (params.mlockall) {
148 if (mlockall(MCL_CURRENT | MCL_FUTURE))
149 err(EXIT_FAILURE, "mlockall");
150 }
151
152 if (!params.nthreads) /* default to the number of CPUs */
153 params.nthreads = cpu->nr;
154
155 worker = calloc(params.nthreads, sizeof(*worker));
156 if (!worker)
157 goto errmem;
158
159 if (!params.fshared)
160 futex_flag = FUTEX_PRIVATE_FLAG;
161
162 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
163 getpid(), params.nthreads, params.nfutexes, params.fshared ? "shared":"private", params.runtime);
164
165 init_stats(&throughput_stats);
166 pthread_mutex_init(&thread_lock, NULL);
167 pthread_cond_init(&thread_parent, NULL);
168 pthread_cond_init(&thread_worker, NULL);
169
170 threads_starting = params.nthreads;
171 pthread_attr_init(&thread_attr);
172 gettimeofday(&bench__start, NULL);
173 for (i = 0; i < params.nthreads; i++) {
174 worker[i].tid = i;
175 worker[i].futex = calloc(params.nfutexes, sizeof(*worker[i].futex));
176 if (!worker[i].futex)
177 goto errmem;
178
179 CPU_ZERO(&cpuset);
180 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
181
182 ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset);
183 if (ret)
184 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
185
186 ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
187 (void *)(struct worker *) &worker[i]);
188 if (ret)
189 err(EXIT_FAILURE, "pthread_create");
190
191 }
192 pthread_attr_destroy(&thread_attr);
193
194 pthread_mutex_lock(&thread_lock);
195 while (threads_starting)
196 pthread_cond_wait(&thread_parent, &thread_lock);
197 pthread_cond_broadcast(&thread_worker);
198 pthread_mutex_unlock(&thread_lock);
199
200 sleep(params.runtime);
201 toggle_done(0, NULL, NULL);
202
203 for (i = 0; i < params.nthreads; i++) {
204 ret = pthread_join(worker[i].thread, NULL);
205 if (ret)
206 err(EXIT_FAILURE, "pthread_join");
207 }
208
209 /* cleanup & report results */
210 pthread_cond_destroy(&thread_parent);
211 pthread_cond_destroy(&thread_worker);
212 pthread_mutex_destroy(&thread_lock);
213
214 for (i = 0; i < params.nthreads; i++) {
215 unsigned long t = bench__runtime.tv_sec > 0 ?
216 worker[i].ops / bench__runtime.tv_sec : 0;
217 update_stats(&throughput_stats, t);
218 if (!params.silent) {
219 if (params.nfutexes == 1)
220 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
221 worker[i].tid, &worker[i].futex[0], t);
222 else
223 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
224 worker[i].tid, &worker[i].futex[0],
225 &worker[i].futex[params.nfutexes-1], t);
226 }
227
228 zfree(&worker[i].futex);
229 }
230
231 print_summary();
232
233 free(worker);
234 free(cpu);
235 return ret;
236 errmem:
237 err(EXIT_FAILURE, "calloc");
238 }
239