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List:       kwin
Subject:    Re: __GL_YIELD
From:       Lubos Lunak <l.lunak () suse ! cz>
Date:       2007-05-02 17:02:39
Message-ID: 200705021902.40023.l.lunak () suse ! cz
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On Wednesday 02 of May 2007, Rivo Laks wrote:
> 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.

 Ok. It doesn't seem to make any visible difference here, but maybe that's 
just me. If it helps, we probably should include it. However, if I'm getting 
it right, this needs to be set before the app is even launched (which is why 
Beryl restarts). That however doesn't work with KWin and kdeinit. We would 
probably have to load openGL dynamically instead of linking against it :-/.

> 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)?

 You mean keeping the window contents even when the window is hidden 
(minimized/on another virtual desktop/whatever)? I have an experimental patch 
for that but there are still some problems.

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

-- 
Lubos Lunak
KDE developer
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SUSE LINUX, s.r.o.   e-mail: l.lunak@suse.cz , l.lunak@kde.org
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Czech Republic       http//www.suse.cz
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