[Intel-gfx] intel_gpu_top profiles

Daniel J Blueman daniel.blueman at gmail.com
Fri Oct 30 22:54:55 CET 2009

On Fri, Oct 30, 2009 at 6:25 PM, Eric Anholt <eric at anholt.net> wrote:
> On Fri, 2009-10-30 at 12:29 +0000, Peter Clifton wrote:
>> Hi guys..
>> intel_gpu_top seemed like it has been a well kept secret.. I discovered
>> it today, and took some profiles of the circuit board layout package I'm
>> working on.
>> Can anyone suggest whether there appears to be "room for improvement"? I
>> couldn't spot any obvious bottle-neck. I'm surprised that the pixel
>> shader is seeing any use, (even without compiz), as I'm just using
>> boring fixed-function stuff with no texturing, no lighting, nothing
>> fancy..
> I'd been meaning to type this up for a while, and your mail convinced me
> to do so.  Here's a new wiki page:
> http://dri.freedesktop.org/wiki/IntelPerformanceTuning
> Does this help?  Are there parts that are unclear and confusing?
>> Screen-captures of the profiles available here:
>> http://www2.eng.cam.ac.uk/~pcjc2/geda/intel_gpu_top_profiles/
>> http://www2.eng.cam.ac.uk/~pcjc2/geda/intel_gpu_top_profiles/intel_gpu_load_displaylist_no_compiz_PCB.png
>> http://www2.eng.cam.ac.uk/~pcjc2/geda/intel_gpu_top_profiles/intel_gpu_top_displaylist_compiz_PCB.png
>> http://www2.eng.cam.ac.uk/~pcjc2/geda/intel_gpu_top_profiles/intel_gpu_top_no_displaylist_compiz_PCB.png
>> http://www2.eng.cam.ac.uk/~pcjc2/geda/intel_gpu_top_profiles/intel_gpu_top_no_displaylist_no_compiz_PCB.png
> OK, so this shows that the GPU is almost entirely idle, time to pull out
> perf and see what's going wrong.

Would any missing write barriers (ie wmb on x86) cause this behaviour,
eg if GPU commands are written to memory-mapped I/O pages with
write-combining page flags?

Daniel J Blueman

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