opengl under Xgl

David Reveman davidr at
Wed Apr 26 03:15:30 PDT 2006

On Wed, 2006-04-26 at 02:38 +0100, Ioannis Nousias wrote:
> I've seen reports from people having good performance with opengl apps 
> (like glxgears) under Xgl and people having low scores, as if no 
> acceleration is active. Unfortunately I'm one of the latter. I've only 
> tested xgl with low spec hardware such as a GeForce 4200 Go, a i855GM 
> and a Radeon 9000Pro. They all exhibit the same behavior. Good (for 
> their capabilities that is) performance for opengl apps under xorg, 
> terrible performance under Xgl. 
> The question is, why is compiz running so well? Am I doing something 
> wrong? I compile most of the stuff myself using the latest versions out 
> there (dri drivers, mesa-dri, drm, xgl, compiz, even the kernel). I'll 
> be happy to provide any relevant info required to track this problem. 
> It's just that I don't know where to start from. So if anyone has a clue 
> / can point me to the right direction, that will be really appreciated.

For accelerating GLX rendering to redirected windows, pbuffers or FBOs
are required (-accel glx or -accel glx:pbuffer to enable in Xgl). If
your card/driver doesn't support that, then you'll get software GL.
glxinfo should indicate if software GL or native GL is used.

compiz is always accelerated as it's not drawing to a redirected window
but to the root window.


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