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

[David Ahern <david.ahern@oracle.com>]

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@redhat.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