opengl under Xgl

Ioannis Nousias s0238762 at
Fri Apr 28 19:15:14 PDT 2006

David Reveman wrote:
> 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.
> -David
ah! yes indeed. According to this
the open source radeon driver (which I'm using for my 9000pro) does not 
support pbuffer or fbo. For my nVidia card, I get normal FPS, but 100% 
cpu utilisation with glxgears under Xgl.

though a different subject, after a recent update on xgl+compiz, 
occasionally I get artifacts on "tip"windows or  menu windows, which 
sometimes cause the server to crash. The artifacts look like a 
distortion  or sometime the windows appear almost black, with some 
colourful pixels.

and last thing, is there a proper fix for the SDL transparency issue 
under Xgl?


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