EXA performance problem

[Maarten Maathuis]

On Mon, Nov 28, 2011 at 7:43 AM, Maarten Maathuis <madman2003 at gmail.com> wrote:
> On Mon, Nov 28, 2011 at 2:41 AM, Christoph Bartoschek
> <bartoschek at or.uni-bonn.de> wrote:
>> I have new information. I am no longer sure whether it is a problem with
>> EXA.
>>
>> I have a testcase that currently takes 90 seconds to draw all rectangles. I
>> see that in damage.c two functions are mainly used:
>>
>> damagePolyRectangle
>> damagePolyFillRectangle
>>
>> The first function calls for each given rectangle up to four times
>> damageDamageBox (pDrawable, &box, pGC->subWindowMode);
>> which adds the box to a region. The function then calls damageRegionAppend.
>>
>> This part takes in sum 30 seconds of my testcase. I think the code has
>> quadratic behaviour here becuase it adds rectangle by rectangle instead of
>> first adding them to a region and then calling damageRegionAppend. I think
>> removing the quadratic behaviour can reduce the runtime significantly.
>>
>> About 60 seconds are spent in the calls
>>
>> (*pGC->ops->PolyRectangle)(pDrawable, pGC, nRects, pRects);
>> (*pGC->ops->PolyFillRect)(pDrawable, pGC, nRects, pRects);
>>
>> However I do not yet know why they are so slow.
>>
>> Is damage.c part of EXA?
>>
>> Christoph
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>>
>
> No, damage is an extention, it is called by EXA, it's probably adding
> all you rectangles to a damage region used to determine how much data
> is actually valid (needed for ram<-->vram migrations for example).
>
> One thing that just comes to mind, if you are rendering a million
> rectangles, how many of those do you actually see on your screen?
>
> Anyway, you can try optimizing damaga, exa and either fb or mi (for
> PolyRectangle PolyFillRect software ops). I don't know how efficient
> the region code is at reducing the number of rectangles if they
> overlap, a region is built up out of rectangles as well.
>
> --
> Far away from the primal instinct, the song seems to fade away, the
> river get wider between your thoughts and the things we do and say.
>

s/damaga/damage and s/extention/extension and s/you rectangles/your rectangles

It was too early in the morning :-)

-- 
Far away from the primal instinct, the song seems to fade away, the
river get wider between your thoughts and the things we do and say.