1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
*
* futex-wake: Block a bunch of threads on a futex and wake'em up, N at a time.
*
* This program is particularly useful to measure the latency of nthread wakeups
* in non-error situations: all waiters are queued and all wake calls wakeup
* one or more tasks, and thus the waitqueue is never empty.
*/
/* For the CLR_() macros */
#include <string.h>
#include <pthread.h>
#include <signal.h>
#include "../util/stat.h"
#include <subcmd/parse-options.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/time64.h>
#include <errno.h>
#include <perf/cpumap.h>
#include "bench.h"
#include "futex.h"
#include <err.h>
#include <stdlib.h>
#include <sys/time.h>
/* all threads will block on the same futex */
static u_int32_t futex1 = 0;
/*
* How many wakeups to do at a time.
* Default to 1 in order to make the kernel work more.
*/
static unsigned int nwakes = 1;
pthread_t *worker;
static bool done = false, silent = false, fshared = false;
static pthread_mutex_t thread_lock;
static pthread_cond_t thread_parent, thread_worker;
static struct stats waketime_stats, wakeup_stats;
static unsigned int threads_starting, nthreads = 0;
static int futex_flag = 0;
static const struct option options[] = {
OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
OPT_UINTEGER('w', "nwakes", &nwakes, "Specify amount of threads to wake at once"),
OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
OPT_END()
};
static const char * const bench_futex_wake_usage[] = {
"perf bench futex wake <options>",
NULL
};
static void *workerfn(void *arg __maybe_unused)
{
pthread_mutex_lock(&thread_lock);
threads_starting--;
if (!threads_starting)
pthread_cond_signal(&thread_parent);
pthread_cond_wait(&thread_worker, &thread_lock);
pthread_mutex_unlock(&thread_lock);
while (1) {
if (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
break;
}
pthread_exit(NULL);
return NULL;
}
static void print_summary(void)
{
double waketime_avg = avg_stats(&waketime_stats);
double waketime_stddev = stddev_stats(&waketime_stats);
unsigned int wakeup_avg = avg_stats(&wakeup_stats);
printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
wakeup_avg,
nthreads,
waketime_avg / USEC_PER_MSEC,
rel_stddev_stats(waketime_stddev, waketime_avg));
}
static void block_threads(pthread_t *w,
pthread_attr_t thread_attr, struct perf_cpu_map *cpu)
{
cpu_set_t cpuset;
unsigned int i;
threads_starting = nthreads;
/* create and block all threads */
for (i = 0; i < nthreads; i++) {
CPU_ZERO(&cpuset);
CPU_SET(cpu->map[i % cpu->nr], &cpuset);
if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
err(EXIT_FAILURE, "pthread_create");
}
}
static void toggle_done(int sig __maybe_unused,
siginfo_t *info __maybe_unused,
void *uc __maybe_unused)
{
done = true;
}
int bench_futex_wake(int argc, const char **argv)
{
int ret = 0;
unsigned int i, j;
struct sigaction act;
pthread_attr_t thread_attr;
struct perf_cpu_map *cpu;
argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
if (argc) {
usage_with_options(bench_futex_wake_usage, options);
exit(EXIT_FAILURE);
}
cpu = perf_cpu_map__new(NULL);
if (!cpu)
err(EXIT_FAILURE, "calloc");
memset(&act, 0, sizeof(act));
sigfillset(&act.sa_mask);
act.sa_sigaction = toggle_done;
sigaction(SIGINT, &act, NULL);
if (!nthreads)
nthreads = cpu->nr;
worker = calloc(nthreads, sizeof(*worker));
if (!worker)
err(EXIT_FAILURE, "calloc");
if (!fshared)
futex_flag = FUTEX_PRIVATE_FLAG;
printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
"waking up %d at a time.\n\n",
getpid(), nthreads, fshared ? "shared":"private", &futex1, nwakes);
init_stats(&wakeup_stats);
init_stats(&waketime_stats);
pthread_attr_init(&thread_attr);
pthread_mutex_init(&thread_lock, NULL);
pthread_cond_init(&thread_parent, NULL);
pthread_cond_init(&thread_worker, NULL);
for (j = 0; j < bench_repeat && !done; j++) {
unsigned int nwoken = 0;
struct timeval start, end, runtime;
/* create, launch & block all threads */
block_threads(worker, thread_attr, cpu);
/* make sure all threads are already blocked */
pthread_mutex_lock(&thread_lock);
while (threads_starting)
pthread_cond_wait(&thread_parent, &thread_lock);
pthread_cond_broadcast(&thread_worker);
pthread_mutex_unlock(&thread_lock);
usleep(100000);
/* Ok, all threads are patiently blocked, start waking folks up */
gettimeofday(&start, NULL);
while (nwoken != nthreads)
nwoken += futex_wake(&futex1, nwakes, futex_flag);
gettimeofday(&end, NULL);
timersub(&end, &start, &runtime);
update_stats(&wakeup_stats, nwoken);
update_stats(&waketime_stats, runtime.tv_usec);
if (!silent) {
printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
j + 1, nwoken, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
}
for (i = 0; i < nthreads; i++) {
ret = pthread_join(worker[i], NULL);
if (ret)
err(EXIT_FAILURE, "pthread_join");
}
}
/* cleanup & report results */
pthread_cond_destroy(&thread_parent);
pthread_cond_destroy(&thread_worker);
pthread_mutex_destroy(&thread_lock);
pthread_attr_destroy(&thread_attr);
print_summary();
free(worker);
return ret;
}
|
