[cairo] [PATCH 2/2] gl: Remove GL fixed-function matrix usage.

[Chris Wilson]

On Wed, 2 Feb 2011 04:00:01 +0200, Alexandros Frantzis <alexandros.frantzis at linaro.org> wrote:
> in order to get a better view of the situation, I added some simple
> instrumentation to cairo-gl. The results for sufficiently long runs of
> various benchmark are:
> 
>                                                           vertices/update 
>                      Vertices  CPU xforms Uniform updates (xforms/update)
> firefox-talos-gfx    365825262 121941756  2262973         160 (53)        
> gnome-system-monitor 126700506 42233504   47897           2645 (881)
> evolution            7236340   2412114    86182           83 (28)
> poppler              15121080  5040360    253440          60 (20)
> 
> Where:
>     Vertices: How many vertices where emitted
>     CPU xforms: the number of point transforms on the CPU with Eric's patch
> 	            (always ~3xVertices)
> 	Uniform updates: the number of ModelViewProjection uniform updates
> 	                 with my branch
> 	vertices/update: Ratio of vertices per uniform update
> 	xforms/update: Ratio of CPU transforms per uniform update

Before I dive in, does your MVP branch include the matrix uniform updates
for computing the src/mask tcoords from the single dst vertex?

This debate will only get interesting when we have vertex shaders. Then we
really can compare the CPU/GPU tradeoff (and quality of driver
implementation). There are important secondary effects from reducing the
amount of vertex data being pushed out from cairo, which should give
additional benefit from vertex shaders and moving the burden to the
driver/GPU.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre