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Subject: Re: [PATCH] Enhance perf to collect KVM guest os statistics from
 host side
From: Peter Zijlstra <peterz@infradead.org>
To: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>, Soeren Sandmann <sandmann@daimi.au.dk>,
       Joerg Roedel <joro@8bytes.org>, Ingo Molnar <mingo@elte.hu>,
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       Zachary Amsden <zamsden@redhat.com>, zhiteng.huang@intel.com,
       Fr??d??ric Weisbecker <fweisbec@gmail.com>,
       Pekka Enberg <penberg@cs.helsinki.fi>
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Date: Tue, 23 Mar 2010 16:23:01 +0100
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On Tue, 2010-03-23 at 11:10 -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, Mar 23, 2010 at 02:49:01PM +0100, Andi Kleen escreveu:
> > Soeren Sandmann <sandmann@daimi.au.dk> writes:
> > > To fix that problem, it seems like we need some way to have python
> > > export what is going on. Maybe the same mechanism could be used to
> > > both access what is going on in qemu and python.
> > 
> > oprofile already has an interface to let JITs export
> > information about the JITed code. C Python is not a JIT,
> > but presumably one of the python JITs could do it.
> > 
> > http://oprofile.sourceforge.net/doc/devel/index.html
> > 
> > I know it's not envogue anymore and you won't be a approved 
> > cool kid if you do, but you could just use oprofile? 
> 
> perf also has supports for this and Pekka Enberg's jato uses it:
> 
> http://penberg.blogspot.com/2009/06/jato-has-profiler.html

Right, we need to move that into a library though (always meant to do
that, never got around to doing it).

That way the app can link against a dso with weak empty stubs and have
perf record LD_PRELOAD a version that has a suitable implementation.

That all has the advantage of not exposing the actual interface like we
do now.