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Message-ID: <20231004204741.985422-1-namhyung@kernel.org>
Date: Wed, 4 Oct 2023 13:47:41 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: [PATCH] perf bench sched pipe: Add -G/--cgroups option
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.
# 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@...nel.org>
---
tools/perf/Documentation/perf-bench.txt | 19 +++++
tools/perf/bench/sched-pipe.c | 93 +++++++++++++++++++++++++
2 files changed, 112 insertions(+)
diff --git a/tools/perf/Documentation/perf-bench.txt b/tools/perf/Documentation/perf-bench.txt
index ca5789625cd2..8331bd28b10e 100644
--- a/tools/perf/Documentation/perf-bench.txt
+++ b/tools/perf/Documentation/perf-bench.txt
@@ -124,6 +124,14 @@ Options of *pipe*
--loop=::
Specify number of loops.
+-G::
+--cgroups=::
+Names of cgroups for sender and receiver, separated by a comma.
+This is useful to check cgroup context switching overhead.
+Note that perf doesn't create nor delete the cgroups, so users should
+make sure that the cgroups exist and are accessible before use.
+
+
Example of *pipe*
^^^^^^^^^^^^^^^^^
@@ -141,6 +149,17 @@ Example of *pipe*
Total time:0.016 sec
16.948000 usecs/op
59004 ops/sec
+
+% perf bench sched pipe -G AAA,BBB
+(executing 1000000 pipe operations between cgroups)
+# Running 'sched/pipe' benchmark:
+# Executed 1000000 pipe operations between two processes
+
+ Total time: 6.886 [sec]
+
+ 6.886208 usecs/op
+ 145217 ops/sec
+
---------------------
SUITES FOR 'syscall'
diff --git a/tools/perf/bench/sched-pipe.c b/tools/perf/bench/sched-pipe.c
index a960e7a93aec..1103fd658d5d 100644
--- a/tools/perf/bench/sched-pipe.c
+++ b/tools/perf/bench/sched-pipe.c
@@ -11,6 +11,7 @@
*/
#include <subcmd/parse-options.h>
#include "bench.h"
+#include "util/cgroup.h"
#include <unistd.h>
#include <stdio.h>
@@ -19,6 +20,7 @@
#include <sys/wait.h>
#include <string.h>
#include <errno.h>
+#include <fcntl.h>
#include <assert.h>
#include <sys/time.h>
#include <sys/types.h>
@@ -40,9 +42,55 @@ static int loops = LOOPS_DEFAULT;
/* Use processes by default: */
static bool threaded;
+static struct cgroup *cgrp_send = NULL;
+static struct cgroup *cgrp_recv = NULL;
+
+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");
+ return -1;
+ }
+
+ q = strchr(p, ',');
+ if (q == NULL) {
+ fprintf(stderr, "it should have two cgroup names: %s", p);
+ goto out;
+ }
+ *q = '\0';
+
+ cgrp_send = cgroup__new(p, /*do_open=*/true);
+ if (cgrp_send == NULL) {
+ fprintf(stderr, "cannot open sender cgroup: %s", p);
+ goto out;
+ }
+
+ /* skip ',' */
+ q++;
+
+ cgrp_recv = cgroup__new(q, /*do_open=*/true);
+ if (cgrp_recv == NULL) {
+ fprintf(stderr, "cannot open receiver cgroup: %s", q);
+ 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()
};
@@ -51,12 +99,54 @@ static const char * const bench_sched_pipe_usage[] = {
NULL
};
+static void enter_cgroup(struct cgroup *cgrp)
+{
+ char buf[32];
+ int fd, len;
+ pid_t pid;
+
+ if (cgrp == NULL)
+ return;
+
+ 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.procs", O_WRONLY);
+ else
+ fd = openat(cgrp->fd, "cgroup.threads", O_WRONLY);
+
+ /* try cgroup v1 if failed */
+ if (fd < 0)
+ fd = openat(cgrp->fd, "tasks", O_WRONLY);
+
+ if (fd < 0) {
+ printf("failed to open cgroup file in %s\n", cgrp->name);
+ return;
+ }
+
+ if (write(fd, buf, len) != len)
+ printf("cannot enter to cgroup: %s\n", cgrp->name);
+ close(fd);
+}
+
static void *worker_thread(void *__tdata)
{
struct thread_data *td = __tdata;
int m = 0, i;
int ret;
+ if (td->nr)
+ enter_cgroup(cgrp_send);
+ else
+ enter_cgroup(cgrp_recv);
+
for (i = 0; i < loops; i++) {
if (!td->nr) {
ret = read(td->pipe_read, &m, sizeof(int));
@@ -147,6 +237,9 @@ int bench_sched_pipe(int argc, const char **argv)
gettimeofday(&stop, NULL);
timersub(&stop, &start, &diff);
+ cgroup__put(cgrp_send);
+ cgroup__put(cgrp_recv);
+
switch (bench_format) {
case BENCH_FORMAT_DEFAULT:
printf("# Executed %d pipe operations between two %s\n\n",
--
2.42.0.609.gbb76f46606-goog
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