cregit-Linux how code gets into the kernel

Release 4.10 tools/perf/bench/futex-lock-pi.c

Directory: tools/perf/bench
 * Copyright (C) 2015 Davidlohr Bueso.

/* 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 <errno.h>
#include "bench.h"
#include "futex.h"

#include <err.h>
#include <stdlib.h>
#include <sys/time.h>

struct worker {
int tid;
u_int32_t *futex;
pthread_t thread;
unsigned long ops;

static u_int32_t global_futex = 0;

static struct worker *worker;

static unsigned int nsecs = 10;

static bool silent = false, multi = false;

static bool done = false, fshared = false;

static unsigned int ncpus, nthreads = 0;

static int futex_flag = 0;

struct timeval start, end, runtime;

static pthread_mutex_t thread_lock;

static unsigned int threads_starting;

static struct stats throughput_stats;

static pthread_cond_t thread_parent, thread_worker;

static const struct option options[] = {
	OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
	OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
	OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
	OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
	OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),

static const char * const bench_futex_lock_pi_usage[] = {
	"perf bench futex lock-pi <options>",

static void print_summary(void) { unsigned long avg = avg_stats(&throughput_stats); double stddev = stddev_stats(&throughput_stats); printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), (int) runtime.tv_sec); }


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static void toggle_done(int sig __maybe_unused, siginfo_t *info __maybe_unused, void *uc __maybe_unused) { /* inform all threads that we're done for the day */ done = true; gettimeofday(&end, NULL); timersub(&end, &start, &runtime); }


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static void *workerfn(void *arg) { struct worker *w = (struct worker *) arg; unsigned long ops = w->ops; 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); do { int ret; again: ret = futex_lock_pi(w->futex, NULL, futex_flag); if (ret) { /* handle lock acquisition */ if (!silent) warn("thread %d: Could not lock pi-lock for %p (%d)", w->tid, w->futex, ret); if (done) break; goto again; } usleep(1); ret = futex_unlock_pi(w->futex, futex_flag); if (ret && !silent) warn("thread %d: Could not unlock pi-lock for %p (%d)", w->tid, w->futex, ret); ops++; /* account for thread's share of work */ } while (!done); w->ops = ops; return NULL; }


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static void create_threads(struct worker *w, pthread_attr_t thread_attr) { cpu_set_t cpu; unsigned int i; threads_starting = nthreads; for (i = 0; i < nthreads; i++) { worker[i].tid = i; if (multi) { worker[i].futex = calloc(1, sizeof(u_int32_t)); if (!worker[i].futex) err(EXIT_FAILURE, "calloc"); } else worker[i].futex = &global_futex; 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, &thread_attr, workerfn, &worker[i])) err(EXIT_FAILURE, "pthread_create"); } }


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int bench_futex_lock_pi(int argc, const char **argv, const char *prefix __maybe_unused) { int ret = 0; unsigned int i; struct sigaction act; pthread_attr_t thread_attr; argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0); if (argc) goto err; ncpus = sysconf(_SC_NPROCESSORS_ONLN); nsecs = futexbench_sanitize_numeric(nsecs); 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]: %d threads doing pi lock/unlock pairing for %d secs.\n\n", getpid(), nthreads, nsecs); init_stats(&throughput_stats); pthread_mutex_init(&thread_lock, NULL); pthread_cond_init(&thread_parent, NULL); pthread_cond_init(&thread_worker, NULL); threads_starting = nthreads; pthread_attr_init(&thread_attr); gettimeofday(&start, NULL); create_threads(worker, thread_attr); pthread_attr_destroy(&thread_attr); 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); sleep(nsecs); toggle_done(0, NULL, NULL); for (i = 0; i < nthreads; i++) { ret = pthread_join(worker[i].thread, 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); for (i = 0; i < nthreads; i++) { unsigned long t = worker[i].ops/runtime.tv_sec; update_stats(&throughput_stats, t); if (!silent) printf("[thread %3d] futex: %p [ %ld ops/sec ]\n", worker[i].tid, worker[i].futex, t); if (multi) free(worker[i].futex); } print_summary(); free(worker); return ret; err: usage_with_options(bench_futex_lock_pi_usage, options); exit(EXIT_FAILURE); }


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Directory: tools/perf/bench
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