lkml.org 
[lkml]   [2010]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: disabling group leader perf_event

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Mon, 2010-09-06 at 14:58 +0300, Avi Kivity wrote:
> > On 09/06/2010 02:54 PM, Peter Zijlstra wrote:
> > >
> > >> Basically, to read() all events in one go. I have many of them.
> > >>
> > >> My current problem is that I have an event (kvm_exit) which I want to
> > >> drill down by looking at a field (exit_reason). So I create lots of
> > >> separate perf_events with a filter for each reason:
> > >> kvm_exit(exit_reason==0), kvm_exit(exit_reason==1), etc. But filters
> > >> are fairly slow (can have ~60 such events on AMD), so I want to make
> > >> this drill-down optional.
> > > Yeah, filters suck.
> >
> > Any idea why? I saw nothing obvious in the code, except that there
> > is lots of it.
>
> It filters after it does all the hard work of creating the trace
> event, instead of before.

Btw., that's an implementational property of filters that would be nice
to fix.

If it's not doable within CPP then outside of it.

Ingo


\
 
 \ /
  Last update: 2010-09-06 14:43    [W:0.101 / U:0.428 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site