perf bench: Add sched-pipe.c: Benchmark for pipe() system call

/*

 *

 * builtin-bench-pipe.c

 *

 * pipe: Benchmark for pipe()

 *

 * 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"

#include "../builtin.h"

#include "bench.h"

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <signal.h>

#include <sys/wait.h>

#include <linux/unistd.h>

#include <string.h>

#include <errno.h>

#include <assert.h>

#include <sys/time.h>

#define LOOPS_DEFAULT 1000000

static int loops = LOOPS_DEFAULT;

static int simple = 0;

static const struct option options[] = {

	OPT_INTEGER('l', "loop", &loops,

		    "Specify number of loops"),

	OPT_BOOLEAN('s', "simple-output", &simple,

		    "Do simple output (this maybe useful for"

		    "processing by scripts or graph tools like gnuplot)"),

	OPT_END()

};

static const char * const bench_sched_pipe_usage[] = {

	"perf bench sched pipe <options>",

	NULL

};

int bench_sched_pipe(int argc, const char **argv,

		     const char *prefix __used)

{

	int pipe_1[2], pipe_2[2];

	int m = 0, i;

	struct timeval start, stop, diff;

	unsigned long long result_usec = 0;

	/*

	 * why does "ret" exist?

	 * discarding returned value of read(), write()

	 * causes error in building environment for perf

	 */

	int ret;

	pid_t pid;

	argc = parse_options(argc, argv, options,

			     bench_sched_pipe_usage, 0);

	assert(!pipe(pipe_1));

	assert(!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));

		}

	}

	gettimeofday(&stop, NULL);

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

	if (pid)

		return 0;

	if (simple)

		printf("%lu.%03lu\n",

		       diff.tv_sec, diff.tv_usec / 1000);

	else {

		printf("(executing %d pipe operations between two tasks)\n\n",

			loops);

		result_usec = diff.tv_sec * 1000000;

		result_usec += diff.tv_usec;

		printf("\tTotal time:%lu.%03lu sec\n",

		       diff.tv_sec, diff.tv_usec / 1000);

		printf("\t\t%lf usecs/op\n",

		       (double)result_usec / (double)loops);

		printf("\t\t%d ops/sec\n",

		       (int)((double)loops /

			     ((double)result_usec / (double)1000000)));

	}

	return 0;

}