2 * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
4 * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
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.
11 /* For the CLR_() macros */
18 #include <linux/compiler.h>
19 #include <linux/kernel.h>
22 #include "../util/stat.h"
23 #include <subcmd/parse-options.h>
30 static unsigned int nthreads
= 0;
31 static unsigned int nsecs
= 10;
32 /* amount of futexes per thread */
33 static unsigned int nfutexes
= 1024;
34 static bool fshared
= false, done
= false, silent
= false;
35 static int futex_flag
= 0;
37 struct timeval start
, end
, runtime
;
38 static pthread_mutex_t thread_lock
;
39 static unsigned int threads_starting
;
40 static struct stats throughput_stats
;
41 static pthread_cond_t thread_parent
, thread_worker
;
50 static const struct option options
[] = {
51 OPT_UINTEGER('t', "threads", &nthreads
, "Specify amount of threads"),
52 OPT_UINTEGER('r', "runtime", &nsecs
, "Specify runtime (in seconds)"),
53 OPT_UINTEGER('f', "futexes", &nfutexes
, "Specify amount of futexes per threads"),
54 OPT_BOOLEAN( 's', "silent", &silent
, "Silent mode: do not display data/details"),
55 OPT_BOOLEAN( 'S', "shared", &fshared
, "Use shared futexes instead of private ones"),
59 static const char * const bench_futex_hash_usage
[] = {
60 "perf bench futex hash <options>",
64 static void *workerfn(void *arg
)
67 struct worker
*w
= (struct worker
*) arg
;
69 unsigned long ops
= w
->ops
; /* avoid cacheline bouncing */
71 pthread_mutex_lock(&thread_lock
);
73 if (!threads_starting
)
74 pthread_cond_signal(&thread_parent
);
75 pthread_cond_wait(&thread_worker
, &thread_lock
);
76 pthread_mutex_unlock(&thread_lock
);
79 for (i
= 0; i
< nfutexes
; i
++, ops
++) {
81 * We want the futex calls to fail in order to stress
82 * the hashing of uaddr and not measure other steps,
83 * such as internal waitqueue handling, thus enlarging
84 * the critical region protected by hb->lock.
86 ret
= futex_wait(&w
->futex
[i
], 1234, NULL
, futex_flag
);
88 (!ret
|| errno
!= EAGAIN
|| errno
!= EWOULDBLOCK
))
89 warn("Non-expected futex return call");
97 static void toggle_done(int sig __maybe_unused
,
98 siginfo_t
*info __maybe_unused
,
99 void *uc __maybe_unused
)
101 /* inform all threads that we're done for the day */
103 gettimeofday(&end
, NULL
);
104 timersub(&end
, &start
, &runtime
);
107 static void print_summary(void)
109 unsigned long avg
= avg_stats(&throughput_stats
);
110 double stddev
= stddev_stats(&throughput_stats
);
112 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
113 !silent
? "\n" : "", avg
, rel_stddev_stats(stddev
, avg
),
114 (int) runtime
.tv_sec
);
117 int bench_futex_hash(int argc
, const char **argv
)
121 struct sigaction act
;
122 unsigned int i
, ncpus
;
123 pthread_attr_t thread_attr
;
124 struct worker
*worker
= NULL
;
126 argc
= parse_options(argc
, argv
, options
, bench_futex_hash_usage
, 0);
128 usage_with_options(bench_futex_hash_usage
, options
);
132 ncpus
= sysconf(_SC_NPROCESSORS_ONLN
);
134 sigfillset(&act
.sa_mask
);
135 act
.sa_sigaction
= toggle_done
;
136 sigaction(SIGINT
, &act
, NULL
);
138 if (!nthreads
) /* default to the number of CPUs */
141 worker
= calloc(nthreads
, sizeof(*worker
));
146 futex_flag
= FUTEX_PRIVATE_FLAG
;
148 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
149 getpid(), nthreads
, nfutexes
, fshared
? "shared":"private", nsecs
);
151 init_stats(&throughput_stats
);
152 pthread_mutex_init(&thread_lock
, NULL
);
153 pthread_cond_init(&thread_parent
, NULL
);
154 pthread_cond_init(&thread_worker
, NULL
);
156 threads_starting
= nthreads
;
157 pthread_attr_init(&thread_attr
);
158 gettimeofday(&start
, NULL
);
159 for (i
= 0; i
< nthreads
; i
++) {
161 worker
[i
].futex
= calloc(nfutexes
, sizeof(*worker
[i
].futex
));
162 if (!worker
[i
].futex
)
166 CPU_SET(i
% ncpus
, &cpu
);
168 ret
= pthread_attr_setaffinity_np(&thread_attr
, sizeof(cpu_set_t
), &cpu
);
170 err(EXIT_FAILURE
, "pthread_attr_setaffinity_np");
172 ret
= pthread_create(&worker
[i
].thread
, &thread_attr
, workerfn
,
173 (void *)(struct worker
*) &worker
[i
]);
175 err(EXIT_FAILURE
, "pthread_create");
178 pthread_attr_destroy(&thread_attr
);
180 pthread_mutex_lock(&thread_lock
);
181 while (threads_starting
)
182 pthread_cond_wait(&thread_parent
, &thread_lock
);
183 pthread_cond_broadcast(&thread_worker
);
184 pthread_mutex_unlock(&thread_lock
);
187 toggle_done(0, NULL
, NULL
);
189 for (i
= 0; i
< nthreads
; i
++) {
190 ret
= pthread_join(worker
[i
].thread
, NULL
);
192 err(EXIT_FAILURE
, "pthread_join");
195 /* cleanup & report results */
196 pthread_cond_destroy(&thread_parent
);
197 pthread_cond_destroy(&thread_worker
);
198 pthread_mutex_destroy(&thread_lock
);
200 for (i
= 0; i
< nthreads
; i
++) {
201 unsigned long t
= worker
[i
].ops
/runtime
.tv_sec
;
202 update_stats(&throughput_stats
, t
);
205 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
206 worker
[i
].tid
, &worker
[i
].futex
[0], t
);
208 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
209 worker
[i
].tid
, &worker
[i
].futex
[0],
210 &worker
[i
].futex
[nfutexes
-1], t
);
213 free(worker
[i
].futex
);
221 err(EXIT_FAILURE
, "calloc");