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Date
SubjectRe: [PATCH] perf bench:Fix bench/sched-pipe.c to wait child process
From
From: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Subject: [PATCH] perf bench:Fix bench/sched-pipe.c to wait child process
Date: Mon, 9 Nov 2009 12:13:08 +0900

Sorry, the title lacks space after "perf bench:".
I'll send new fixed one, please discard this.

> Fixed bench/sched-pipe.c to avoid the below case
> notified by Ingo Molnar,
>
> ---
>
> $ ./perf bench sched pipe
> (executing 1000000 pipe operations between two tasks)
>
> Total time:4.898 sec
> $ 4.898586 usecs/op
> 204140 ops/sec
>
> the shell prompt came back before the usecs/op and ops/sec line was
> printed. Process teardown race, lack of wait() or so?
>
> ---
>
> This caused by lack of calling waitpid() by parent process,
> so I added it.
>
> Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Jiri Kosina <jkosina@suse.cz>
> ---
> tools/perf/bench/sched-pipe.c | 10 +++++++---
> 1 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/bench/sched-pipe.c b/tools/perf/bench/sched-pipe.c
> index 3214ed2..6a29100 100644
> --- a/tools/perf/bench/sched-pipe.c
> +++ b/tools/perf/bench/sched-pipe.c
> @@ -26,6 +26,7 @@
> #include <errno.h>
> #include <assert.h>
> #include <sys/time.h>
> +#include <sys/types.h>
>
> #define LOOPS_DEFAULT 1000000
> static int loops = LOOPS_DEFAULT;
> @@ -58,8 +59,8 @@ int bench_sched_pipe(int argc, const char **argv,
> * discarding returned value of read(), write()
> * causes error in building environment for perf
> */
> - int ret;
> - pid_t pid;
> + int ret, wait_stat;
> + pid_t pid, retpid;
>
> argc = parse_options(argc, argv, options,
> bench_sched_pipe_usage, 0);
> @@ -87,8 +88,11 @@ int bench_sched_pipe(int argc, const char **argv,
> gettimeofday(&stop, NULL);
> timersub(&stop, &start, &diff);
>
> - if (pid)
> + if (pid) {
> + retpid = waitpid(pid, &wait_stat, 0);
> + assert((retpid == pid) && WIFEXITED(wait_stat));
> return 0;
> + }
>
> if (simple)
> printf("%lu.%03lu\n",
> --
> 1.6.5.2
>
>


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