[Intel-gfx] [PATCH] drm/i915: add a tracepoint for gpu frequency changes

[Daniel Vetter]

On Sat, Sep 01, 2012 at 07:44:17PM -0700, Arjan van de Ven wrote:
> On 9/1/2012 6:36 PM, Ben Widawsky wrote:
> 
> > It depends on what you're trying to measure. I think this patch is quite useful but I think I'll make you defend your patch now since you're the maintainer and you took
> > your own patch and you're shooting down my idea. So please tell me what PowerTOP should do with this patch other than notice we're stuck (and furthermore, even if we're
> > stuck, what should it tell us to do)?
> 
> what I would like to do, as the powertop guy.... is to show frequency stats similar to how we do that
> for CPUs. E.g. as close as to actual as we can get.
> few questions:
> 1) Can I read the momentary frequency somewhere?
> (it's great to get change events, but I also need a start frequency, otherwise I have a gap in
> knowledge from start of measurement to first change event)

Oops, forgotten about this, but it looks like Ben has already volunteered
himself for those ;-)

> 2) Can I read a "hardware average" somewhere, similar to what we can do for cpus ?

Afaik, there's nothing. But since the cpu controls the gpu freq
completely, you can just compute those yourselves from the tracepoints.
Together with the rc6 residency timers we already expose this should give
a neat overview of how busy the gpu is and how much power it blows through
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48