On Thu, May 26, 2011 at 11:43:23AM +0200, Peter Zijlstra wrote:
>
> That's just wrong.. the reason you're wanting to have this timer is to
> avoid the RAPL MSRs from overflowing and you loosing offsets, right?
>
> But the above is actually forcing the event to create samples on a
> totally unrelated time base.
>
> RAPL should fail to create a sampling event since it doesn't have the
> capability to trigger overflow interrupts based on its events.
>
> If you want a timer, add one, but don't do this.
>
> If you expect you actually want to sample, use this event as part of a
> group and add a sampling event in there and use PERF_FORMAT_GROUP, Matt
> was working on patches to make perf-record capable of this.
Yep, I have some unfinished patches around here somewhere...
*rummage*
OK, they're in this repository on the perf/group-events branch,
git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/sh-2.6.git
Obviously since I last touched them in November of last year they're
more than likely not going to apply cleanly to tip, and perhaps more
importantly, I don't think I ever submitted them to LKML for review.
Rui, I'll try to look at your patch series over the weekend and get my
sampling patches into a state where they can be submitted for review
and used by the intel_rapl driver. Does that sound OK?
Or if you want to take a more proactive approach, you're welcome to
finish and submit them ;-)
--
Matt Fleming, Intel Open Source Technology Center
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