Intel driver - DRI profiling

Lukas Hejtmanek xhejtman at
Fri Mar 14 06:20:00 PDT 2008

On Fri, Mar 14, 2008 at 01:01:56AM +0100, Jakob Bornecrantz wrote:
> I'll try to explain as good as I can understand it myself.
> The drm_bo_vm_nopfn (from here on called nopfn) is the function in the
> kernel which handles page faults for clients accessing buffers who as
> had its pages removed from its vm[1,2,3]. Playing around with buffer
> pages and changing caching (which is sometimes required) is a rather
> costly operation. If I remember things correctly it does not map all
> pages on create & first drmBoMap call, and since nopfn does not map
> all the pages at once several calls will be done to it on accessing a
> whole buffer that is large.

Thank you for explaination. However, I do not understand why this should
happen when running glxgears. 
> CPU vs GPU unbalance, your CPU is feeding the GPU faster then the it
> can processes the commands and therefore it will sleep waiting for it
> to complete the rendering. I'm guessing you only used the nvidia
> driver on shiny high powered GPU's :-), Try to resize the glxgears
> window to realy small size (not to small tho) and see the CPU usage go
> up.

OK, I did it. I resized the window to 70x70 pixels and I have two observations:
1) CPU usage is about 60%
2) it makes only 30% more FPS as the default size.

Don't you thing this is at least odd?

Lukáš Hejtmánek

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