The All-Singing, All-Dancing XCompMGR

Tomeu Vizoso tomeu at
Mon May 3 03:17:31 EDT 2010

On Fri, Apr 30, 2010 at 22:35, Jon Nettleton <jon.nettleton at> wrote:
>> I think our next steps should be to:
>>  * quantify the memory difference (both total and per-window) against
>>   not running xcompmgr.  We were already running with the composite X
>>   extension on, so I think the increase may be small.
>>  * work out whether we think the "frame pieces" drop shadow, and drop
>>   shadow in general, are an improvement -- we should ask the Sugar
>>   Design Team for their opinion on this too.
>> Jon N, any opinions from the openchrome end on turning on xcompmgr?
> Currently compositing on the VX855 with openchrome would work, but is
> extemely inefficient.  The openchrome support for the VX855 only
> supports XAA until we get DRI and DMA sorted out.  Compositing on XAA
> is really inefficient as only System Memory to VRAM actions are
> accelerated by the RENDER extension.
> Overall compositing is visually a nice improvement, but almost always
> at a cost of CPU and power.  I also think xcompmgr is not the right
> piece of software.  It is really old and missing a lot of the love
> needed for a good compositing manager to work seamlessly.  Mainly it
> is missing un-redirecting fullscreen windows and overlays causing
> video playback to be quite expensive, and OpenGL to be unreliable.
> Back when Thomas first wrote EXA support for the openchrome we found
> that the bare minimum you needed for descent compositing performance
> was 64MB of video ram.  This is doable but we also have to realize we
> are at a disadvantage because we run at a relative high resolution
> 1200x900.
> If we were going the compositing route I would probably suggest the
> project look into using a simple compositing window manager like XFWM
> from the XFCE project.  Their code was originally an import of
> xcompmgr, but they have done a great job improving it over the years.
> But I think that is another conversation entirely.

We could reuse the work done in Sugar 0.86 when we moved to metacity
from matchbox. Or just use metacity which is also a compositing
windowm manager.



> Jon
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