1 files changed, 29 insertions, 86 deletions

diff --git a/tools/perf/bench/sched-pipe.c b/tools/perf/bench/sched-pipe.c
index 07a8d76..69cfba8 100644
--- a/tools/perf/bench/sched-pipe.c
+++ b/tools/perf/bench/sched-pipe.c
@@ -7,7 +7,9 @@
  * 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"
@@ -26,24 +28,12 @@
 #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 int loops = LOOPS_DEFAULT;
 
 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_INTEGER('l', "loop", &loops,
+		    "Specify number of loops"),
 	OPT_END()
 };
 
@@ -52,37 +42,13 @@ 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)
+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?
@@ -92,66 +58,43 @@ int bench_sched_pipe(int argc, const char **argv, const char *prefix __maybe_unu
 	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));
 
-	gettimeofday(&start, NULL);
-
-	for (t = 0; t < nr_threads; t++) {
-		td = threads + t;
+	pid = fork();
+	assert(pid >= 0);
 
-		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];
-		}
-	}
-
-
-	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;
+	gettimeofday(&start, NULL);
 
-			ret = pthread_join(td->pthread, NULL);
-			BUG_ON(ret);
+	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 {
-		pid = fork();
-		assert(pid >= 0);
-
-		if (!pid) {
-			worker_thread(threads + 0);
-			exit(0);
-		} else {
-			worker_thread(threads + 1);
+		for (i = 0; i < loops; i++) {
+			ret = write(pipe_1[1], &m, sizeof(int));
+			ret = read(pipe_2[0], &m, sizeof(int));
 		}
-
-		retpid = waitpid(pid, &wait_stat, 0);
-		assert((retpid == pid) && WIFEXITED(wait_stat));
 	}
 
 	gettimeofday(&stop, NULL);
 	timersub(&stop, &start, &diff);
 
+	if (pid) {
+		retpid = waitpid(pid, &wait_stat, 0);
+		assert((retpid == pid) && WIFEXITED(wait_stat));
+	} else {
+		exit(0);
+	}
+
 	switch (bench_format) {
 	case BENCH_FORMAT_DEFAULT:
-		printf("# Executed %d pipe operations between two %s\n\n",
-			loops, threaded ? "threads" : "processes");
+		printf("# Executed %d pipe operations between two tasks\n\n",
+			loops);
 
 		result_usec = diff.tv_sec * 1000000;
 		result_usec += diff.tv_usec;