lkml.org 
[lkml]   [2012]   [Dec]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [GIT PULL] perf changes for v3.8
On 12/17/12 3:20 AM, Gleb Natapov wrote:
> Does the regression happen because of commit 20b279ddb38c. If it does I
> think it is safe to revert it. KVM disables PEBS during guest entry now, so
> VMs shouldn't be blowing up (they do not in my testing) and if they still
> do we can disable the counter that has PEBS enabled on a guest entry too.
> Yes, if user runs "perf record -e cycles:ppG" he will not know that
> kernel ignored :pp modifier (with 20b279ddb38c he will get an error), but
> at least old binaries will continue working and new binaries can do the
> checking in userspace.
>

Your patch alone was not enough. Start here:
https://lkml.org/lkml/2012/7/12/3

And from your response:
https://lkml.org/lkml/2012/7/12/337

"Do not run perf kvm. It does not set exclude_guest and :p and :pp is
not compatible with guest profiling and should be disallowed. Again
Peter's patch takes care of this."

20b279ddb38c is Peter's patch -- kernel side enforcement that
exclude_guest needs to be set when using precise mode.

David


\
 
 \ /
  Last update: 2012-12-22 20:41    [W:0.140 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site