From kwin  Wed May 02 09:49:23 2007
From: Rivo Laks <rivolaks () hot ! ee>
Date: Wed, 02 May 2007 09:49:23 +0000
To: kwin
Subject: Re: __GL_YIELD
Message-Id: <200705021249.23391.rivolaks () hot ! ee>
X-MARC-Message: https://marc.info/?l=kwin&m=117809931809786

Ühel kenal päeval (esmaspäev 30 aprill 2007) kirjutas Lubos Lunak:
>  Hello,
>
>  does somebody know about details about %subj%? This
> http://lists.freedesktop.org/archives/compiz/2007-April/001965.html thread
> discusses some internal NVidia shell variable that should improve
> performance.

Hi

From what I could find in the net, it tells the driver not to "yield it's 
timeslice" which seems to mean that driver won't donate it's own execution 
time to other programs. This would result in better performance, especially 
under heavy cpu load.

Experimenting shows that setting  __GL_YIELD="NOTHING"  really does improve 
(visible) performance. Especially animations feel a lot snappier with it, 
possibly because window repaints are more delayed towards the end of 
animation. So while the animation (e.g. desktop switch) is in progress, you 
mostly see just a white/grey window background and usually the window repaint 
is completed only at the end of the animation.
BTW, can't we just keep the window texture around (window mapped or whatever 
the correct term is) instead of repainting it every time it's shown (e.g. on 
desktop switch)?

So IMHO it would probably be a good idea to use __GL_YIELD when doing GL 
compositing.

Rivo
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