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Subject[PATCH] perf bench sched: Add --threaded option

* Namhyung Kim <namhyung@kernel.org> wrote:

> Hi Ingo,
>
> Just a few nitpicks...
>
> On Tue, 17 Sep 2013 13:42:56 +0200, Ingo Molnar wrote:
> > 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
>
> Why not just make it boolean? IMHO the integer argument can confuse
> users as they can think it a number of threads..

Agreed, fixed.

Btw., we should allow "--flag 0/1" type of input for bool options as well,
it's easier for scripting. Any other integer should be rejected, and
non-integer should be interpreted as the next option.

In addition, it would be nice to allow the following two aliases as well:

--non-flag
--dont-flag

So that the following can be written:

--threaded
--non-threaded

or, if the option name is a verb:

--use-threads
--dont-use-threads

Instead of forcing the following incorrect grammar on users:

--no-threaded
--no-use-threads

> > +static void *worker_thread(void *__tdata)
> > +{
> > + struct thread_data *td = __tdata;
>
> Whitespace damaged. Otherwise looks good to me!

Fixed this too - new version attached.

Thanks,

Ingo

--------------------------------->
Subject: perf bench sched: Add --threaded option
From: Ingo Molnar <mingo@kernel.org>
Date: Tue, 17 Sep 2013 13:42:56 +0200

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
# 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
# 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@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Link: http://lkml.kernel.org/r/20130917114256.GA31159@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
tools/perf/bench/sched-pipe.c | 115 +++++++++++++++++++++++++++++++-----------
1 file changed, 86 insertions(+), 29 deletions(-)

Index: tip/tools/perf/bench/sched-pipe.c
===================================================================
--- tip.orig/tools/perf/bench/sched-pipe.c
+++ tip/tools/perf/bench/sched-pipe.c
@@ -7,9 +7,7 @@
* 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 "../perf.h"
#include "../util/util.h"
#include "../util/parse-options.h"
@@ -28,12 +26,24 @@
#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 loops = LOOPS_DEFAULT;
+
+/* Use processes by default: */
+static bool threaded;

static const struct option options[] = {
- OPT_INTEGER('l', "loop", &loops,
- "Specify number of loops"),
+ OPT_INTEGER('l', "loop", &loops, "Specify number of loops"),
+ OPT_BOOLEAN('T', "threaded", &threaded, "Specify threads/process based task setup"),
OPT_END()
};

@@ -42,13 +52,37 @@ static const char * const bench_sched_pi
NULL
};

-int bench_sched_pipe(int argc, const char **argv,
- const char *prefix __maybe_unused)
+static void *worker_thread(void *__tdata)
{
- int pipe_1[2], pipe_2[2];
+ 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];
struct timeval start, stop, diff;
unsigned long long result_usec = 0;
+ int nr_threads = 2;
+ int t;

/*
* why does "ret" exist?
@@ -58,43 +92,66 @@ int bench_sched_pipe(int argc, const cha
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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