linux-kernel - Re: [PATCH] perf tools: Fix ppid for non-main thread

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Message-ID: <5526B1F9.3020002@oracle.com>
Date:	Thu, 09 Apr 2015 11:08:09 -0600
From:	David Ahern <david.ahern@...cle.com>
To:	Don Zickus <dzickus@...hat.com>
CC:	acme@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf tools: Fix ppid for non-main thread

On 4/9/15 11:05 AM, Don Zickus wrote:
> 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@...hat.com>
>

I believe this explains the performance delta you noticed with 
specjbb/jvm. Arnaldo is the one that figured out the performance hit is 
from cloning maps; from that analysis I realized what the goof was.

David
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