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 */
17 #include <linux/compiler.h>
18 #include <linux/kernel.h>
21 #include "../util/stat.h"
22 #include <subcmd/parse-options.h>
29 static unsigned int nthreads
= 0;
30 static unsigned int nsecs
= 10;
31 /* amount of futexes per thread */
32 static unsigned int nfutexes
= 1024;
33 static bool fshared
= false, done
= false, silent
= false;
34 static int futex_flag
= 0;
36 struct timeval start
, end
, 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
;
49 static const struct option options
[] = {
50 OPT_UINTEGER('t', "threads", &nthreads
, "Specify amount of threads"),
51 OPT_UINTEGER('r', "runtime", &nsecs
, "Specify runtime (in seconds)"),
52 OPT_UINTEGER('f', "futexes", &nfutexes
, "Specify amount of futexes per threads"),
53 OPT_BOOLEAN( 's', "silent", &silent
, "Silent mode: do not display data/details"),
54 OPT_BOOLEAN( 'S', "shared", &fshared
, "Use shared futexes instead of private ones"),
58 static const char * const bench_futex_hash_usage
[] = {
59 "perf bench futex hash <options>",
63 static void *workerfn(void *arg
)
66 struct worker
*w
= (struct worker
*) arg
;
68 unsigned long ops
= w
->ops
; /* avoid cacheline bouncing */
70 pthread_mutex_lock(&thread_lock
);
72 if (!threads_starting
)
73 pthread_cond_signal(&thread_parent
);
74 pthread_cond_wait(&thread_worker
, &thread_lock
);
75 pthread_mutex_unlock(&thread_lock
);
78 for (i
= 0; i
< nfutexes
; i
++, ops
++) {
80 * We want the futex calls to fail in order to stress
81 * the hashing of uaddr and not measure other steps,
82 * such as internal waitqueue handling, thus enlarging
83 * the critical region protected by hb->lock.
85 ret
= futex_wait(&w
->futex
[i
], 1234, NULL
, futex_flag
);
87 (!ret
|| errno
!= EAGAIN
|| errno
!= EWOULDBLOCK
))
88 warn("Non-expected futex return call");
96 static void toggle_done(int sig __maybe_unused
,
97 siginfo_t
*info __maybe_unused
,
98 void *uc __maybe_unused
)
100 /* inform all threads that we're done for the day */
102 gettimeofday(&end
, NULL
);
103 timersub(&end
, &start
, &runtime
);
106 static void print_summary(void)
108 unsigned long avg
= avg_stats(&throughput_stats
);
109 double stddev
= stddev_stats(&throughput_stats
);
111 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
112 !silent
? "\n" : "", avg
, rel_stddev_stats(stddev
, avg
),
113 (int) runtime
.tv_sec
);
116 int bench_futex_hash(int argc
, const char **argv
,
117 const char *prefix __maybe_unused
)
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
);
133 nsecs
= futexbench_sanitize_numeric(nsecs
);
134 nfutexes
= futexbench_sanitize_numeric(nfutexes
);
136 sigfillset(&act
.sa_mask
);
137 act
.sa_sigaction
= toggle_done
;
138 sigaction(SIGINT
, &act
, NULL
);
140 if (!nthreads
) /* default to the number of CPUs */
143 nthreads
= futexbench_sanitize_numeric(nthreads
);
145 worker
= calloc(nthreads
, sizeof(*worker
));
150 futex_flag
= FUTEX_PRIVATE_FLAG
;
152 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
153 getpid(), nthreads
, nfutexes
, fshared
? "shared":"private", nsecs
);
155 init_stats(&throughput_stats
);
156 pthread_mutex_init(&thread_lock
, NULL
);
157 pthread_cond_init(&thread_parent
, NULL
);
158 pthread_cond_init(&thread_worker
, NULL
);
160 threads_starting
= nthreads
;
161 pthread_attr_init(&thread_attr
);
162 gettimeofday(&start
, NULL
);
163 for (i
= 0; i
< nthreads
; i
++) {
165 worker
[i
].futex
= calloc(nfutexes
, sizeof(*worker
[i
].futex
));
166 if (!worker
[i
].futex
)
170 CPU_SET(i
% ncpus
, &cpu
);
172 ret
= pthread_attr_setaffinity_np(&thread_attr
, sizeof(cpu_set_t
), &cpu
);
174 err(EXIT_FAILURE
, "pthread_attr_setaffinity_np");
176 ret
= pthread_create(&worker
[i
].thread
, &thread_attr
, workerfn
,
177 (void *)(struct worker
*) &worker
[i
]);
179 err(EXIT_FAILURE
, "pthread_create");
182 pthread_attr_destroy(&thread_attr
);
184 pthread_mutex_lock(&thread_lock
);
185 while (threads_starting
)
186 pthread_cond_wait(&thread_parent
, &thread_lock
);
187 pthread_cond_broadcast(&thread_worker
);
188 pthread_mutex_unlock(&thread_lock
);
191 toggle_done(0, NULL
, NULL
);
193 for (i
= 0; i
< nthreads
; i
++) {
194 ret
= pthread_join(worker
[i
].thread
, NULL
);
196 err(EXIT_FAILURE
, "pthread_join");
199 /* cleanup & report results */
200 pthread_cond_destroy(&thread_parent
);
201 pthread_cond_destroy(&thread_worker
);
202 pthread_mutex_destroy(&thread_lock
);
204 for (i
= 0; i
< nthreads
; i
++) {
205 unsigned long t
= worker
[i
].ops
/runtime
.tv_sec
;
206 update_stats(&throughput_stats
, t
);
209 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
210 worker
[i
].tid
, &worker
[i
].futex
[0], t
);
212 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
213 worker
[i
].tid
, &worker
[i
].futex
[0],
214 &worker
[i
].futex
[nfutexes
-1], t
);
217 free(worker
[i
].futex
);
225 err(EXIT_FAILURE
, "calloc");