[Mesa-dev] [PATCH] Add EXT_timer_query to the mesa state tracker and softpipe

[Mathias Fröhlich]

Hi,

On Monday 17 May 2010 20:51:09 Corbin Simpson wrote:
> I'm going to be proactive here, and pull in both this patch and a docs
> update.
Ok.
Now that the infrastructure is there.

My initial aim was to have something to profile the r300g driver.
It already  runs nicer then the classic one for plenty of stuff I tried. But 
that is still up to factors slower than the binary only driver from amd/ati.
So having a clue where to look for improvements is a good thing to do.
Also OpenSceneGraph uses this timers for its helpful graphical scene graph 
profiling aids.

To do that I have been looking into the docs to find a cycle counter or 
something equivalent in the gpu. But so far without luck.
If we have such a counter, we could dump that counter into the query object 
similar to the occlusion query implementation.

Sure we can alternatively trigger a soft interrupt and read the kernel timer 
in the interrupt handler. That would already give nanoseconds timers. But I 
hope that this kind of functionality could be implemented less intrusive as 
this requires changes to the kernel part of the driver I think.

Thoughts?
Knowledge about some undocumented registers fitting that purpose?

... looking at amds windows profiling tools make me believe that there are such 
registers.

Greetings

Mathias