79a3371bdf
The -G/--cgroups option is to put sender and receiver in different cgroups in order to measure cgroup context switch overheads. Users need to make sure the cgroups exist and accessible. The following example should the effect of this change. Please don't forget taskset before the perf bench to measure cgroup switches properly. Otherwise each task would run on a different CPU and generate cgroup switches regardless of this change. # perf stat -e context-switches,cgroup-switches \ > taskset -c 0 perf bench sched pipe -l 10000 > /dev/null Performance counter stats for 'taskset -c 0 perf bench sched pipe -l 10000': 20,001 context-switches 2 cgroup-switches 0.053449651 seconds time elapsed 0.011286000 seconds user 0.041869000 seconds sys # perf stat -e context-switches,cgroup-switches \ > taskset -c 0 perf bench sched pipe -l 10000 -G AAA,BBB > /dev/null Performance counter stats for 'taskset -c 0 perf bench sched pipe -l 10000 -G AAA,BBB': 20,001 context-switches 20,001 cgroup-switches 0.052768627 seconds time elapsed 0.006284000 seconds user 0.046266000 seconds sys Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Link: https://lore.kernel.org/r/20231017202342.1353124-1-namhyung@kernel.org
308 lines
6.3 KiB
C
308 lines
6.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
*
|
|
* sched-pipe.c
|
|
*
|
|
* pipe: Benchmark for pipe()
|
|
*
|
|
* Based on pipe-test-1m.c by Ingo Molnar <mingo@redhat.com>
|
|
* http://people.redhat.com/mingo/cfs-scheduler/tools/pipe-test-1m.c
|
|
* Ported to perf by Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
|
|
*/
|
|
#include <subcmd/parse-options.h>
|
|
#include <api/fs/fs.h>
|
|
#include "bench.h"
|
|
#include "util/cgroup.h"
|
|
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <signal.h>
|
|
#include <sys/wait.h>
|
|
#include <string.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <assert.h>
|
|
#include <sys/time.h>
|
|
#include <sys/types.h>
|
|
#include <sys/syscall.h>
|
|
#include <linux/time64.h>
|
|
|
|
#include <pthread.h>
|
|
|
|
struct thread_data {
|
|
int nr;
|
|
int pipe_read;
|
|
int pipe_write;
|
|
bool cgroup_failed;
|
|
pthread_t pthread;
|
|
};
|
|
|
|
#define LOOPS_DEFAULT 1000000
|
|
static int loops = LOOPS_DEFAULT;
|
|
|
|
/* Use processes by default: */
|
|
static bool threaded;
|
|
|
|
static char *cgrp_names[2];
|
|
static struct cgroup *cgrps[2];
|
|
|
|
static int parse_two_cgroups(const struct option *opt __maybe_unused,
|
|
const char *str, int unset __maybe_unused)
|
|
{
|
|
char *p = strdup(str);
|
|
char *q;
|
|
int ret = -1;
|
|
|
|
if (p == NULL) {
|
|
fprintf(stderr, "memory allocation failure\n");
|
|
return -1;
|
|
}
|
|
|
|
q = strchr(p, ',');
|
|
if (q == NULL) {
|
|
fprintf(stderr, "it should have two cgroup names: %s\n", p);
|
|
goto out;
|
|
}
|
|
*q = '\0';
|
|
|
|
cgrp_names[0] = strdup(p);
|
|
cgrp_names[1] = strdup(q + 1);
|
|
|
|
if (cgrp_names[0] == NULL || cgrp_names[1] == NULL) {
|
|
fprintf(stderr, "memory allocation failure\n");
|
|
goto out;
|
|
}
|
|
ret = 0;
|
|
|
|
out:
|
|
free(p);
|
|
return ret;
|
|
}
|
|
|
|
static const struct option options[] = {
|
|
OPT_INTEGER('l', "loop", &loops, "Specify number of loops"),
|
|
OPT_BOOLEAN('T', "threaded", &threaded, "Specify threads/process based task setup"),
|
|
OPT_CALLBACK('G', "cgroups", NULL, "SEND,RECV",
|
|
"Put sender and receivers in given cgroups",
|
|
parse_two_cgroups),
|
|
OPT_END()
|
|
};
|
|
|
|
static const char * const bench_sched_pipe_usage[] = {
|
|
"perf bench sched pipe <options>",
|
|
NULL
|
|
};
|
|
|
|
static int enter_cgroup(int nr)
|
|
{
|
|
char buf[32];
|
|
int fd, len, ret;
|
|
int saved_errno;
|
|
struct cgroup *cgrp;
|
|
pid_t pid;
|
|
|
|
if (cgrp_names[nr] == NULL)
|
|
return 0;
|
|
|
|
if (cgrps[nr] == NULL) {
|
|
cgrps[nr] = cgroup__new(cgrp_names[nr], /*do_open=*/true);
|
|
if (cgrps[nr] == NULL)
|
|
goto err;
|
|
}
|
|
cgrp = cgrps[nr];
|
|
|
|
if (threaded)
|
|
pid = syscall(__NR_gettid);
|
|
else
|
|
pid = getpid();
|
|
|
|
snprintf(buf, sizeof(buf), "%d\n", pid);
|
|
len = strlen(buf);
|
|
|
|
/* try cgroup v2 interface first */
|
|
if (threaded)
|
|
fd = openat(cgrp->fd, "cgroup.threads", O_WRONLY);
|
|
else
|
|
fd = openat(cgrp->fd, "cgroup.procs", O_WRONLY);
|
|
|
|
/* try cgroup v1 if failed */
|
|
if (fd < 0 && errno == ENOENT)
|
|
fd = openat(cgrp->fd, "tasks", O_WRONLY);
|
|
|
|
if (fd < 0)
|
|
goto err;
|
|
|
|
ret = write(fd, buf, len);
|
|
close(fd);
|
|
|
|
if (ret != len) {
|
|
printf("Cannot enter to cgroup: %s\n", cgrp->name);
|
|
return -1;
|
|
}
|
|
return 0;
|
|
|
|
err:
|
|
saved_errno = errno;
|
|
printf("Failed to open cgroup file in %s\n", cgrp_names[nr]);
|
|
|
|
if (saved_errno == ENOENT) {
|
|
char mnt[PATH_MAX];
|
|
|
|
if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event") == 0)
|
|
printf(" Hint: create the cgroup first, like 'mkdir %s/%s'\n",
|
|
mnt, cgrp_names[nr]);
|
|
} else if (saved_errno == EACCES && geteuid() > 0) {
|
|
printf(" Hint: try to run as root\n");
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
static void exit_cgroup(int nr)
|
|
{
|
|
cgroup__put(cgrps[nr]);
|
|
free(cgrp_names[nr]);
|
|
}
|
|
|
|
static void *worker_thread(void *__tdata)
|
|
{
|
|
struct thread_data *td = __tdata;
|
|
int m = 0, i;
|
|
int ret;
|
|
|
|
ret = enter_cgroup(td->nr);
|
|
if (ret < 0) {
|
|
td->cgroup_failed = true;
|
|
return NULL;
|
|
}
|
|
|
|
for (i = 0; i < loops; i++) {
|
|
if (!td->nr) {
|
|
ret = read(td->pipe_read, &m, sizeof(int));
|
|
BUG_ON(ret != sizeof(int));
|
|
ret = write(td->pipe_write, &m, sizeof(int));
|
|
BUG_ON(ret != sizeof(int));
|
|
} else {
|
|
ret = write(td->pipe_write, &m, sizeof(int));
|
|
BUG_ON(ret != sizeof(int));
|
|
ret = read(td->pipe_read, &m, sizeof(int));
|
|
BUG_ON(ret != sizeof(int));
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
int bench_sched_pipe(int argc, const char **argv)
|
|
{
|
|
struct thread_data threads[2] = {};
|
|
struct thread_data *td;
|
|
int pipe_1[2], pipe_2[2];
|
|
struct timeval start, stop, diff;
|
|
unsigned long long result_usec = 0;
|
|
int nr_threads = 2;
|
|
int t;
|
|
|
|
/*
|
|
* why does "ret" exist?
|
|
* discarding returned value of read(), write()
|
|
* causes error in building environment for perf
|
|
*/
|
|
int __maybe_unused ret, wait_stat;
|
|
pid_t pid, retpid __maybe_unused;
|
|
|
|
argc = parse_options(argc, argv, options, bench_sched_pipe_usage, 0);
|
|
|
|
BUG_ON(pipe(pipe_1));
|
|
BUG_ON(pipe(pipe_2));
|
|
|
|
gettimeofday(&start, NULL);
|
|
|
|
for (t = 0; t < nr_threads; t++) {
|
|
td = threads + t;
|
|
|
|
td->nr = t;
|
|
|
|
if (t == 0) {
|
|
td->pipe_read = pipe_1[0];
|
|
td->pipe_write = pipe_2[1];
|
|
} else {
|
|
td->pipe_write = pipe_1[1];
|
|
td->pipe_read = pipe_2[0];
|
|
}
|
|
}
|
|
|
|
if (threaded) {
|
|
for (t = 0; t < nr_threads; t++) {
|
|
td = threads + t;
|
|
|
|
ret = pthread_create(&td->pthread, NULL, worker_thread, td);
|
|
BUG_ON(ret);
|
|
}
|
|
|
|
for (t = 0; t < nr_threads; t++) {
|
|
td = threads + t;
|
|
|
|
ret = pthread_join(td->pthread, NULL);
|
|
BUG_ON(ret);
|
|
}
|
|
} else {
|
|
pid = fork();
|
|
assert(pid >= 0);
|
|
|
|
if (!pid) {
|
|
worker_thread(threads + 0);
|
|
exit(0);
|
|
} else {
|
|
worker_thread(threads + 1);
|
|
}
|
|
|
|
retpid = waitpid(pid, &wait_stat, 0);
|
|
assert((retpid == pid) && WIFEXITED(wait_stat));
|
|
}
|
|
|
|
gettimeofday(&stop, NULL);
|
|
timersub(&stop, &start, &diff);
|
|
|
|
exit_cgroup(0);
|
|
exit_cgroup(1);
|
|
|
|
if (threads[0].cgroup_failed || threads[1].cgroup_failed)
|
|
return 0;
|
|
|
|
switch (bench_format) {
|
|
case BENCH_FORMAT_DEFAULT:
|
|
printf("# Executed %d pipe operations between two %s\n\n",
|
|
loops, threaded ? "threads" : "processes");
|
|
|
|
result_usec = diff.tv_sec * USEC_PER_SEC;
|
|
result_usec += diff.tv_usec;
|
|
|
|
printf(" %14s: %lu.%03lu [sec]\n\n", "Total time",
|
|
(unsigned long) diff.tv_sec,
|
|
(unsigned long) (diff.tv_usec / USEC_PER_MSEC));
|
|
|
|
printf(" %14lf usecs/op\n",
|
|
(double)result_usec / (double)loops);
|
|
printf(" %14d ops/sec\n",
|
|
(int)((double)loops /
|
|
((double)result_usec / (double)USEC_PER_SEC)));
|
|
break;
|
|
|
|
case BENCH_FORMAT_SIMPLE:
|
|
printf("%lu.%03lu\n",
|
|
(unsigned long) diff.tv_sec,
|
|
(unsigned long) (diff.tv_usec / USEC_PER_MSEC));
|
|
break;
|
|
|
|
default:
|
|
/* reaching here is something disaster */
|
|
fprintf(stderr, "Unknown format:%d\n", bench_format);
|
|
exit(1);
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|