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Commit a9faa0ca authored by Ingo Molnar's avatar Ingo Molnar Committed by Arnaldo Carvalho de Melo
Browse files

perf bench sched: Add --threaded 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
 # 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: default avatarIngo 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent b52bc234

tools/perf/bench/sched-pipe.c

+86 −29
Original line number Diff line number Diff line
@@ -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;



/* 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_pipe_usage[] = { 
	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 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));

		}

	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 {

		for (i = 0; i < loops; i++) {

			ret = write(pipe_1[1], &m, sizeof(int));

			ret = read(pipe_2[0], &m, sizeof(int));

			td->pipe_write = pipe_1[1];

			td->pipe_read = pipe_2[0];

		}

	}



	gettimeofday(&stop, NULL);

	timersub(&stop, &start, &diff);



	if (pid) {

		retpid = waitpid(pid, &wait_stat, 0);

		assert((retpid == pid) && WIFEXITED(wait_stat));

	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);



	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;