Re: performance counter 20% error finding retired instruction count

[Ingo Molnar <mingo@elte.hu>]

* 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