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: 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: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/bench/sched-pipe.c b/tools/perf/bench/sched-pipe.c
index 69cfba8d4c6cfb5a0bd402735d3eaa5bfdd7a467..07a8d7646a1549c61699f7311285238ef5ef93cf 100644 (file)
--- a/tools/perf/bench/sched-pipe.c
+++ b/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_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));
-               }
-       } 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;