Commit a0439711 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Arnaldo Carvalho de Melo

perf bench: Add futex-hash microbenchmark

Introduce futexes to perf-bench and add a program that stresses and
measures the kernel's implementation of the hash table.

This is a multi-threaded program that simply measures the amount of
failed futex wait calls - we only want to deal with the hashing
overhead, so a negative return of futex_wait_setup() is enough to do the
trick.

An example run:

  $ perf bench futex hash -t 32
  Run summary [PID 10989]: 32 threads, each operating on 1024 [private] futexes for 10 secs.

  [thread  0] futexes: 0x19d9b10 ... 0x19dab0c [ 418713 ops/sec ]
  [thread  1] futexes: 0x19daca0 ... 0x19dbc9c [ 469913 ops/sec ]
  [thread  2] futexes: 0x19dbe30 ... 0x19dce2c [ 479744 ops/sec ]
  ...
  [thread 31] futexes: 0x19fbb80 ... 0x19fcb7c [ 464179 ops/sec ]

  Averaged 454310 operations/sec (+- 0.84%), total secs = 10
Signed-off-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
Acked-by: default avatarDarren Hart <dvhart@linux.intel.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1387081917-9102-2-git-send-email-davidlohr@hp.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 81827ed8
......@@ -426,6 +426,7 @@ BUILTIN_OBJS += $(OUTPUT)bench/mem-memset-x86-64-asm.o
endif
BUILTIN_OBJS += $(OUTPUT)bench/mem-memcpy.o
BUILTIN_OBJS += $(OUTPUT)bench/mem-memset.o
BUILTIN_OBJS += $(OUTPUT)bench/futex-hash.o
BUILTIN_OBJS += $(OUTPUT)builtin-diff.o
BUILTIN_OBJS += $(OUTPUT)builtin-evlist.o
......
......@@ -31,6 +31,7 @@ extern int bench_sched_pipe(int argc, const char **argv, const char *prefix);
extern int bench_mem_memcpy(int argc, const char **argv,
const char *prefix __maybe_unused);
extern int bench_mem_memset(int argc, const char **argv, const char *prefix);
extern int bench_futex_hash(int argc, const char **argv, const char *prefix);
#define BENCH_FORMAT_DEFAULT_STR "default"
#define BENCH_FORMAT_DEFAULT 0
......
/*
* Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
*
* futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
*
* This program is particularly useful for measuring the kernel's futex hash
* table/function implementation. In order for it to make sense, use with as
* many threads and futexes as possible.
*/
#include "../perf.h"
#include "../util/util.h"
#include "../util/stat.h"
#include "../util/parse-options.h"
#include "../util/header.h"
#include "bench.h"
#include "futex.h"
#include <err.h>
#include <stdlib.h>
#include <sys/time.h>
#include <pthread.h>
static unsigned int nthreads = 0;
static unsigned int nsecs = 10;
/* amount of futexes per thread */
static unsigned int nfutexes = 1024;
static bool fshared = false, done = false, silent = false;
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;
struct worker {
int tid;
u_int32_t *futex;
pthread_t thread;
unsigned long ops;
};
static const struct option options[] = {
OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"),
OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"),
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_hash_usage[] = {
"perf bench futex hash <options>",
NULL
};
static void *workerfn(void *arg)
{
int ret;
unsigned int i;
struct worker *w = (struct worker *) arg;
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 {
for (i = 0; i < nfutexes; i++, w->ops++) {
/*
* We want the futex calls to fail in order to stress
* the hashing of uaddr and not measure other steps,
* such as internal waitqueue handling, thus enlarging
* the critical region protected by hb->lock.
*/
ret = futex_wait(&w->futex[i], 1234, NULL,
fshared ? 0 : FUTEX_PRIVATE_FLAG);
if (!silent &&
(!ret || errno != EAGAIN || errno != EWOULDBLOCK))
warn("Non-expected futex return call");
}
} while (!done);
return NULL;
}
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);
}
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);
}
int bench_futex_hash(int argc, const char **argv,
const char *prefix __maybe_unused)
{
int ret = 0;
cpu_set_t cpu;
struct sigaction act;
unsigned int i, ncpus;
pthread_attr_t thread_attr;
struct worker *worker = NULL;
argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0);
if (argc) {
usage_with_options(bench_futex_hash_usage, options);
exit(EXIT_FAILURE);
}
ncpus = sysconf(_SC_NPROCESSORS_ONLN);
sigfillset(&act.sa_mask);
act.sa_sigaction = toggle_done;
sigaction(SIGINT, &act, NULL);
if (!nthreads) /* default to the number of CPUs */
nthreads = ncpus;
worker = calloc(nthreads, sizeof(*worker));
if (!worker)
goto errmem;
printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
getpid(), nthreads, nfutexes, fshared ? "shared":"private", 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);
for (i = 0; i < nthreads; i++) {
worker[i].tid = i;
worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex));
if (!worker[i].futex)
goto errmem;
CPU_ZERO(&cpu);
CPU_SET(i % ncpus, &cpu);
ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu);
if (ret)
err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
(void *)(struct worker *) &worker[i]);
if (ret)
err(EXIT_FAILURE, "pthread_create");
}
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) {
if (nfutexes == 1)
printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
worker[i].tid, &worker[i].futex[0], t);
else
printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
worker[i].tid, &worker[i].futex[0],
&worker[i].futex[nfutexes-1], t);
}
free(worker[i].futex);
}
print_summary();
free(worker);
return ret;
errmem:
err(EXIT_FAILURE, "calloc");
}
/*
* Glibc independent futex library for testing kernel functionality.
* Shamelessly stolen from Darren Hart <dvhltc@us.ibm.com>
* http://git.kernel.org/cgit/linux/kernel/git/dvhart/futextest.git/
*/
#ifndef _FUTEX_H
#define _FUTEX_H
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <linux/futex.h>
/**
* futex() - SYS_futex syscall wrapper
* @uaddr: address of first futex
* @op: futex op code
* @val: typically expected value of uaddr, but varies by op
* @timeout: typically an absolute struct timespec (except where noted
* otherwise). Overloaded by some ops
* @uaddr2: address of second futex for some ops\
* @val3: varies by op
* @opflags: flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
*
* futex() is used by all the following futex op wrappers. It can also be
* used for misuse and abuse testing. Generally, the specific op wrappers
* should be used instead. It is a macro instead of an static inline function as
* some of the types over overloaded (timeout is used for nr_requeue for
* example).
*
* These argument descriptions are the defaults for all
* like-named arguments in the following wrappers except where noted below.
*/
#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
/**
* futex_wait() - block on uaddr with optional timeout
* @timeout: relative timeout
*/
static inline int
futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflags)
{
return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
}
#endif /* _FUTEX_H */
......@@ -12,6 +12,7 @@
* sched ... scheduler and IPC performance
* mem ... memory access performance
* numa ... NUMA scheduling and MM performance
* futex ... Futex performance
*/
#include "perf.h"
#include "util/util.h"
......@@ -54,6 +55,12 @@ static struct bench mem_benchmarks[] = {
{ NULL, NULL, NULL }
};
static struct bench futex_benchmarks[] = {
{ "hash", "Benchmark for futex hash table", bench_futex_hash },
{ "all", "Test all futex benchmarks", NULL },
{ NULL, NULL, NULL }
};
struct collection {
const char *name;
const char *summary;
......@@ -66,6 +73,7 @@ static struct collection collections[] = {
#ifdef HAVE_LIBNUMA_SUPPORT
{ "numa", "NUMA scheduling and MM benchmarks", numa_benchmarks },
#endif
{"futex", "Futex stressing benchmarks", futex_benchmarks },
{ "all", "All benchmarks", NULL },
{ NULL, NULL, NULL }
};
......
......@@ -12,6 +12,9 @@
#ifndef __NR_perf_event_open
# define __NR_perf_event_open 336
#endif
#ifndef __NR_futex
# define __NR_futex 240
#endif
#endif
#if defined(__x86_64__)
......@@ -23,6 +26,9 @@
#ifndef __NR_perf_event_open
# define __NR_perf_event_open 298
#endif
#ifndef __NR_futex
# define __NR_futex 202
#endif
#endif
#ifdef __powerpc__
......
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