Re: intel_gpu_top decode..

[Peter Clifton <pcjc2@cam.ac.uk>]

On Wed, 2010-10-06 at 15:27 -0700, Eric Anholt wrote:

> Of this, I'd say that you're spending a surprising amount of time in
> texture fetch.  Finding ways to reduce texture bandwidth may pay off,
> assuming that (texture fetch / sampler cache) is the percentage of the
> time you're cache missing.  I'm not sure if that's true or not, though.
> And you said that this data was just for the line drawing, which didn't
> appear to have any texturing going on at all, so I'm just confused.

Indeed, I'm not using texturing at all!

I had assumed the texture unit might have been being used by internal
threads in the GPU for something - or that it might have been due to
other X11 applications running in the background.

I switched off compiz for my benchmarking, and was just using metacity.
Of course, I'm not clear on what cairo / pixman would activate when
drawing. That said.. when _not_ running my benchmark, there is very
little activity from the GPU at all - so it doesn't seem related.

I'm probably doing a few bitmasked glClears of things like the stencil
buffer (part of the compositing / rendering in my app). I can't quite
imagine why, but perhaps mesa is using the texture unit for some
operations.


Thanks for the hint on the busy / stalled figures. That helps interpret
things!

Best wishes,


-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)