Messages in this thread Patch in this message | | | From | Namhyung Kim <> | Subject | [PATCH] perf bench sched pipe: Add -G/--cgroups option | Date | Wed, 4 Oct 2023 13:47:41 -0700 |
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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@kernel.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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