lkml.org 
[lkml]   [2013]   [May]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] perf, x86: Add workaround for MEM_*_RETIRED errata BV98
From
On Wed, May 1, 2013 at 9:13 PM, Andi Kleen <andi@firstfloor.org> wrote:
>> Unfortunately, Andi's patch fails to correct the problem though
>> it is the right approach. As he said, the problem is unfortunately
>
> perf stat -a / record -a / top will work.
>
But it does not for perf stat -a. Look at my example, run it on your machine.

> The case it doesn't fix is per thread when the other sibling
> is not running a counter.
>
> Essentially with the patch you may still get under-counting
> on these specific events if they run per thread (or are really
> unlucky in multiplexing), but never over-counting on anything.
>
> In the past Ingo's guidance was to focus on the most common
> use cases, which I think this patch does.
>
> It would be possible to fix the per thread mode too, but it would
> need quite a bit of new infrastructure and I have doubts that's
> worth it.
>
> -Andi


\
 
 \ /
  Last update: 2013-05-01 22:01    [W:0.894 / U:0.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site