Terrible performance with backing-store enabled.

[Eric Anholt]

On Mon, 2005-07-18 at 12:15 +0200, Clemens Eisserer wrote:
> > This is because backing-store is implemented in a very nasty (but card
> > memory efficient) way.  Using xcompmgr -a will give you what you want,
> > most likely, but with much better performance.  It would be nice to
> > implement these features on top of the Composite extension, I think.
> 
> Thanks for the tip!
> 
> I already tried "xcompmgr -a" but the results where holes in windows
> and rendering artifacts - this is as far as I can imagine related to
> the NVidia driver - I already sent a bug-report to Nvidia.
> However performance is MUCH better using xcompmgr, it gives exactly
> (in terms of performance) what I expected.

If you've got nvidia's RenderAccel turned on, turning it off would be a
good idea (Some have reported stability issues, but the most concerning
to me is that there have been reports of major conformance issues).

> Does anybody know how xcompmgr does manage memory, if e.g. an opengl
> application would like to "upload" textures but almost all memory is
> used by xcompmgr - will the xserver fall back to non-backing windows
> or will the OpenGL application have to use RAM?

That's something determined by your video driver, so I couldn't say.

-- 
Eric Anholt                                     eta at lclark.edu
http://people.freebsd.org/~anholt/              anholt at FreeBSD.org