phenomenally slow performance dragging windows around (was: xrandr: adding a second display to screen 0 [radeon])

[Michel Dänzer]

On Tue, 2008-02-19 at 20:01 +0100, martin f krafft wrote:
> also sprach Michel Dänzer <michel at tungstengraphics.com> [2008.02.19.1854 +0100]:
> > >     Option          "AccelMethod"   "EXA"
> [...]
> > I guess it doesn't happen if you use XAA or if you limit the virtual
> > size to within 2048 in both directions?
> 
> Yes, using XAA fixes this. Thanks, Michel. Do you know of a good
> piece of documentation to read to understand this?

The problem is that EXA is falling back to software rendering for the
root window because its size exceeds the coordinate limits advertised by
the driver (the 3D engine used for RENDER acceleration is limited to
2048 in each dimension).

If you're interested in testing patches, it should be possible to handle
this more cleverly in the driver - the 2D engine used for window moves
can handle up to 8192 in each dimension. We should probably move this to
the xorg-driver-ati list for that purpose though.


-- 
Earthling Michel Dänzer           |          http://tungstengraphics.com
Libre software enthusiast         |          Debian, X and DRI developer