[ubuntu-uk] Compositing performance hit

Andrew Oakley andrew at aoakley.com
Thu Mar 27 10:16:19 GMT 2008

On 26/03/2008, Chris Rowson <christopherrowson at gmail.com> wrote:
 >  Quick question. Does running Ubuntu with compositing enabled effect
 >  the overall performance of the system?
 >  Nvidia Geforce 440

Compositing will not noticeably affect system performance if you have a 
separate hardware 3D graphics card that supports full transparency in 
hardware. I think that any card that is compatible with DirectX7 [1] or 
above will support full transparency. All PCI, AGP and PCI-E Nvidia and 
ATI cards since around 1999 should support full transparency.

Your Nvidia Geforce 440 does support full transparency in separate 
hardware and will run compositing very fast. I actually have the very 
same card on my Ubuntu Dapper machine at home, running Beryl, the 
precursor to Compiz Fusion that is used in Gutsy/Hardy.

If you are using Compiz prior to Hardy Beta (eg. in Gutsy), you may need 
to tweak your xorg.conf video driver settings to prevent full-screen 
video running slowly/jerkily. Various solutions on ubuntuforums.org .

Integrated 3D graphics chips, that are less than three years old, that 
use a mixture of hardware and software, and which are soldered to your 
motherboard, should be fine for most desktop use, but may slow 
considerably when you run full-screen video or full-screen 3D games, 
depending which version of which drivers you are using. For instance, 
until a recent driver update, my laptop with Intel X3100 i965 graphics 
ran full-screen video very jerkily and full-screen 3D games very slowly. 
The solution is to turn off Compiz before running full-screen video or 
3D games; I did this by creating a separate video/gaming desktop 
account. Since the recent Intel driver update, though, full screen video 
works fine with compositing turned on in Hardy Beta.

Integrated graphics chips which are older than 3 years, which use more 
software than hardware, will definitely see a slowdown and possibly, due 
to lack of transparency support, won't work at all. Similarly, any 
AGP/PCI 3D card prior to DirectX7 will probably, due to lack of 
transparency support, not work at all.

Andrew Oakley

[1] DirectX is a Microsoft 3D driver and has little to do with 
Linux/Ubuntu. I use this only as a useful measure of ascertaining 
hardware 3D features, when reading from the side of a box or from a list 
of features on a website, prior to purchase.

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