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SubjectRe: [PATCH] perf tools: Fix ppid for non-main thread
On Thu, Apr 09, 2015 at 12:48:27PM -0400, David Ahern wrote:
> Commit ca6c41c59b9 sets the ppid based on what is read from the
> /proc/pid/status file when synthesizing fork events. This is correct
> thing to do for new processes but not threads of a process. Fix
> ppid for threads to be the main thread when synthesizing fork events
> (ie., assume main thread spawned all sub-threads in a process).

That sounds right. :-) Sorry I should have noticed that a couple of weeks
ago.

Acked-by: Don Zickus <dzickus@redhat.com>

>
> Reported-by: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
> Signed-off-by: David Ahern <david.ahern@oracle.com>
> Cc: Don Zickus <dzickus@redhat.com>
> ---
> tools/perf/util/event.c | 14 ++++++++++++--
> 1 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 186929a..ff866c4 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -183,8 +183,18 @@ static int perf_event__synthesize_fork(struct perf_tool *tool,
> {
> memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);
>
> - event->fork.ppid = ppid;
> - event->fork.ptid = ppid;
> + /*
> + * for main thread set parent to ppid from status file. For other
> + * threads set parent pid to main thread. ie., assume main thread
> + * spawns all threads in a process
> + */
> + if (tgid == pid) {
> + event->fork.ppid = ppid;
> + event->fork.ptid = ppid;
> + } else {
> + event->fork.ppid = tgid;
> + event->fork.ptid = tgid;
> + }
> event->fork.pid = tgid;
> event->fork.tid = pid;
> event->fork.header.type = PERF_RECORD_FORK;
> --
> 1.7.1
>


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