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

[Chris Wilson]

On Sat, 01 Sep 2012 18:16:52 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> On 2012-09-01 12:22, Chris Wilson wrote:
> > On Sat, 01 Sep 2012 11:35:13 -0700, Ben Widawsky <ben at bwidawsk.net> 
> > wrote:
> >> I have no problem with Daniel's patch. It's just a matter of cutting
> >> through some scheduler BS of "when the GPU wants to change 
> >> frequency"
> >> vs. "when we actually change the GPU frequency." I think *both* are
> >> interesting.
> >
> > We already trace the interrupt, which has been invaluable in
> > debugging. And there is no other source currently... :)
> > -Chris
> 
> No we do not trace it (/me is looking on cgit, so perhaps a bit error 
> prone). Sure we trace GT interrupts, but not pm interrupts (again, 
> unless I am missing something via code browsing on the web).

Oh we definitely do otherwise it would have been a bit difficult to have
noticed that we woke up every 10ms to service a PM event that we then
ignore...

> Furthermore, even if we have added a generic interrupt trace event and 
> I've missed it: I think it's still nice to have a power/performance 
> specific one for users like powerTOP, as opposed to driver developers.

As complete BS as GPU op/s? If you can find a tracepoint that is
actionable from within powertop, go for it.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre