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List:       freedesktop-xorg
Subject:    Re: EXA
From:       Lukas Hejtmanek <xhejtman () ics ! muni ! cz>
Date:       2007-08-07 11:50:44
Message-ID: 20070807115043.GF4070 () ics ! muni ! cz
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On Tue, Aug 07, 2007 at 11:30:46AM +0200, Michel Dänzer wrote:
> > 
> > Well, the performance difference between XAA and EXA seems to be the
> > following:
> > XAA uses always pixman_blt_mmx while EXA uses combination of accelerator
> > CopyArea and memcpy.
> 
> The attached patch seems to help here, how does it work for you?

Yes! It definitely helps, EXA now runs at the *same* speed as XAA (i.e.,
1600FPS), hope it will be included in mainline. Thanks a lot!

> > Another point is why exaPrepareAccess calls exaWaitSync, is it really
> > necessary?

> Yes, for serializing intermixed GPU and CPU operations.

So the i915 chip does not support something like pipelining? And is it
theoretically possible to change the I830WaitLpRing function not to use busy
waiting?

> P.S. I still doubt this is the bottleneck of your virtual desktop
> switching, as the numbers you're getting translate to filling the screen
> in just tens of milliseconds.

OK. Now I try to profile overall desktop load and compare it with EXA.

-- 
Lukáš Hejtmánek
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