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

From: David Ahern
Date: Thu Apr 09 2015 - 13:08:22 EST

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

Acked-by: Don Zickus<dzickus@xxxxxxxxxx>

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.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at