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Date: Tue, 17 Sep 2013 13:42:56 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...radead.org>
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Namhyung Kim <namhyung.kim@....com>,
Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH] perf bench sched: Add --threaded 0/1 option
Allow the measurement of thread versus process context switch performance.
The default stays at 'process' based measurement, like lmbench's lat_ctx
benchmark.
Sample output:
comet:~/tip/tools/perf> taskset 1 ./perf bench sched pipe --threaded 0
# Running sched/pipe benchmark...
# Executed 1000000 pipe operations between two processes
Total time: 4.138 [sec]
4.138729 usecs/op
241620 ops/sec
comet:~/tip/tools/perf> taskset 1 ./perf bench sched pipe --threaded 1
# Running sched/pipe benchmark...
# Executed 1000000 pipe operations between two threads
Total time: 3.667 [sec]
3.667667 usecs/op
272652 ops/sec
Signed-off-by: Ingo Molnar <mingo@...nel.org>
diff --git a/tools/perf/bench/sched-pipe.c b/tools/perf/bench/sched-pipe.c
index 69cfba8..7630dc6 100644
--- a/tools/perf/bench/sched-pipe.c
+++ b/tools/perf/bench/sched-pipe.c
@@ -28,12 +28,25 @@
#include <sys/time.h>
#include <sys/types.h>
+#include <pthread.h>
+
+struct thread_data {
+ int nr;
+ int pipe_read;
+ int pipe_write;
+ pthread_t pthread;
+};
+
#define LOOPS_DEFAULT 1000000
static int loops = LOOPS_DEFAULT;
+static int threaded = 0;
+
static const struct option options[] = {
OPT_INTEGER('l', "loop", &loops,
"Specify number of loops"),
+ OPT_INTEGER('T', "threaded", &threaded,
+ "Specify threaded/process based task setup"),
OPT_END()
};
@@ -42,13 +55,38 @@ static const char * const bench_sched_pipe_usage[] = {
NULL
};
+static void *worker_thread(void *__tdata)
+{
+ struct thread_data *td = __tdata;
+ int m = 0, i;
+ int ret;
+
+ 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,
const char *prefix __maybe_unused)
{
+ struct thread_data threads[2], *td;
int pipe_1[2], pipe_2[2];
- int m = 0, i;
struct timeval start, stop, diff;
unsigned long long result_usec = 0;
+ int nr_threads = 2;
+ int t;
/*
* why does "ret" exist?
@@ -58,43 +96,66 @@ int bench_sched_pipe(int argc, const char **argv,
int __maybe_unused ret, wait_stat;
pid_t pid, retpid __maybe_unused;
- argc = parse_options(argc, argv, options,
- bench_sched_pipe_usage, 0);
+ argc = parse_options(argc, argv, options, bench_sched_pipe_usage, 0);
BUG_ON(pipe(pipe_1));
BUG_ON(pipe(pipe_2));
- pid = fork();
- assert(pid >= 0);
-
gettimeofday(&start, NULL);
- if (!pid) {
- for (i = 0; i < loops; i++) {
- ret = read(pipe_1[0], &m, sizeof(int));
- ret = write(pipe_2[1], &m, sizeof(int));
- }
- } else {
- for (i = 0; i < loops; i++) {
- ret = write(pipe_1[1], &m, sizeof(int));
- ret = read(pipe_2[0], &m, sizeof(int));
+ 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];
}
}
- gettimeofday(&stop, NULL);
- timersub(&stop, &start, &diff);
- if (pid) {
+ 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));
- } else {
- exit(0);
}
+ gettimeofday(&stop, NULL);
+ timersub(&stop, &start, &diff);
+
switch (bench_format) {
case BENCH_FORMAT_DEFAULT:
- printf("# Executed %d pipe operations between two tasks\n\n",
- loops);
+ printf("# Executed %d pipe operations between two %s\n\n",
+ loops, threaded ? "threads" : "processes");
result_usec = diff.tv_sec * 1000000;
result_usec += diff.tv_usec;
--
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