Date: Thu, 25 Jun 2009 11:13:24 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vince Weaver <vince@deater.net>, Paul Mackerras <paulus@samba.org>,
       linux-kernel@vger.kernel.org
Subject: Re: performance counter 20% error finding retired instruction count
Message-ID: <20090625091324.GA16860@elte.hu>
References: <Pine.LNX.4.64.0906240937120.10620@pianoman.cluster.toy> <20090624151010.GA12799@elte.hu> <Pine.LNX.4.64.0906242200000.12718@pianoman.cluster.toy> <1245912600.31755.21.camel@twins>
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* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> On Wed, 2009-06-24 at 22:12 -0400, Vince Weaver wrote:
> > 
> > It's also nice to be able to skip the loader overhead, as the 
> > loader can change from system to system and makes it hard to 
> > compare counters across various machines.  Though it sounds like 
> > the perf utility isn't going to be supporting this anytime soon.
> 
> Feel free to contribute such if you think its important.

I'd be glad to review and test any resulting patches from Vince - 
and/or help out with pointers where to start and help out there's 
any roadblocks along the way.

The kernel side bits can be found in v2.6.31-rc1, in 
kernel/perf_counter.c, include/linux/perf_counter.h and 
arch/x86/kernel/cpu/perf_counter.c. We tried to keep the code as 
hackable as possible.

The tooling bits can be found in tools/perf/ in the kernel repo. 
builtin-stat.c contains the 'perf stat' bits.

Thanks,

	Ingo
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