From: David Ahern <dsahern@gmail.com>
To: Don Zickus <dzickus@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linux-kernel@vger.kernel.org, Joe Mario <jmario@redhat.com>,
Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH v2] perf tool: Fix ppid for synthesized fork events
Date: Fri, 27 Mar 2015 14:10:54 -0600 [thread overview]
Message-ID: <5515B94E.6020706@gmail.com> (raw)
In-Reply-To: <20150327194941.GG162412@redhat.com>
On 3/27/15 1:49 PM, Don Zickus wrote:
> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
> index 1c8fbc9..7ee3823 100644
> --- a/tools/perf/util/thread.c
> +++ b/tools/perf/util/thread.c
> @@ -187,6 +187,7 @@ static int thread__clone_map_groups(struct thread *thread,
> if (thread->pid_ == parent->pid_)
> return 0;
There's your answer ... the 2 lines above.
>
> + printf("DON:\n");
> /* But this one is new process, copy maps. */
> for (i = 0; i < MAP__NR_TYPES; ++i)
> if (map_groups__clone(thread->mg, parent->mg, i) < 0)
>
> before David's patch, we do _not_ see any DON markers. After David's patch
> we see a 1:1 match of DON markers to the number of threads currently running
> in the system.
Your "speed up" is based on the assumption that all synthesized threads
are their own parent which is wrong. ie., ppid != tgid of the process.
Before ppid was getting initialized to -1. If you just make that change
to revert to the -1:
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index d5efa5092ce6..ce4ca061c2e5 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -150,8 +150,8 @@ static int perf_event__synthesize_fork(struct
perf_tool *tool,
{
memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);
- event->fork.ppid = tgid;
- event->fork.ptid = tgid;
+ event->fork.ppid = -1;
+ event->fork.ptid = -1;
event->fork.pid = tgid;
event->fork.tid = pid;
event->fork.header.type = PERF_RECORD_FORK;
You see the "DON" messages.
David
next prev parent reply other threads:[~2015-03-27 20:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-25 16:51 [PATCH v2] perf tool: Fix ppid for synthesized fork events David Ahern
2015-03-25 19:15 ` Don Zickus
2015-03-25 19:55 ` David Ahern
2015-03-25 20:26 ` Don Zickus
2015-03-26 21:11 ` Don Zickus
2015-03-26 21:37 ` David Ahern
2015-03-27 13:10 ` Don Zickus
2015-03-27 14:03 ` David Ahern
2015-03-27 14:20 ` Arnaldo Carvalho de Melo
2015-03-27 19:49 ` Don Zickus
2015-03-27 20:09 ` Arnaldo Carvalho de Melo
2015-03-27 20:10 ` David Ahern [this message]
2015-03-27 20:25 ` Don Zickus
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