linux_dsm_epyc7002/tools/perf/bench/futex-wake.c
Davidlohr Bueso 60758d6668 perf bench futex: Sanitize numeric parameters
This gets rid of oddities such as:

  perf bench futex hash -t -4
  perf: calloc: Cannot allocate memory

Runtime (and many more) are equally busted, i.e. run for bogus amounts of
time. Just use the abs, instead of, for example errorring out.

Committer note:

After the patch:

  $ perf bench futex hash -t -4
  # Running 'futex/hash' benchmark:
  Run summary [PID 10178]: 4 threads, each operating on 1024 [private] futexes for 10 secs.

  [thread  0] futexes: 0x34f9fa0 ... 0x34faf9c [ 4702208 ops/sec ]
  [thread  1] futexes: 0x34fb140 ... 0x34fc13c [ 4707020 ops/sec ]
  [thread  2] futexes: 0x34fc2e0 ... 0x34fd2dc [ 4711526 ops/sec ]
  [thread  3] futexes: 0x34fd480 ... 0x34fe47c [ 4709683 ops/sec ]

  Averaged 4707609 operations/sec (+- 0.04%), total secs = 10
  $

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/1477342613-9938-3-git-send-email-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-10-25 09:50:53 -03:00

211 lines
5.5 KiB
C

/*
* 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 <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 "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 ncpus, 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)
{
cpu_set_t cpu;
unsigned int i;
threads_starting = nthreads;
/* create and block all threads */
for (i = 0; i < nthreads; i++) {
CPU_ZERO(&cpu);
CPU_SET(i % ncpus, &cpu);
if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
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,
const char *prefix __maybe_unused)
{
int ret = 0;
unsigned int i, j;
struct sigaction act;
pthread_attr_t thread_attr;
argc = parse_options(argc, argv, options, bench_futex_wake_usage, 0);
if (argc) {
usage_with_options(bench_futex_wake_usage, options);
exit(EXIT_FAILURE);
}
ncpus = sysconf(_SC_NPROCESSORS_ONLN);
nwakes = futexbench_sanitize_numeric(nwakes);
sigfillset(&act.sa_mask);
act.sa_sigaction = toggle_done;
sigaction(SIGINT, &act, NULL);
if (!nthreads)
nthreads = ncpus;
else
nthreads = futexbench_sanitize_numeric(nthreads);
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);
/* 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;
}