radeon EXA performance questions

Michel Dänzer michel at tungstengraphics.com
Tue Aug 5 08:46:39 PDT 2008

On Mon, 2008-08-04 at 22:35 +0200, Simon Thum wrote:
> Michel Dänzer wrote:
> > On Fri, 2008-08-01 at 12:40 +0200, Simon Thum wrote:
> >> Maybe it makes sense to put a similar constraint into EXA pixmap 
> >> migration that my patch (previous mail) had caused in XAA? Is that 
> >> possible somehow?
> > 
> > It would be possible, but the effect may not be comparable, as EXA and
> > XAA use offscreen pixmaps completely differently.
> Yeah, I hacked a thing up but got nothing but display corruption. 

Then you didn't do it correctly. :)

I think the easiest way to limit offscreen usage to a given width and
height is to change the driver EXA initialization to

    info->exa->maxX = MAX_OFFSCREEN_WIDTH;
    info->exa->maxY = MAX_OFFSCREEN_HEIGHT;
    info->exa->maxPitchBytes = 4 * MAX_OFFSCREEN_WIDTH;

Note however that EXA on the xserver master branch (which is recommended
for EXA performance considerations) uses a 1024 pixel wide pixmap for
the glyph cache, and AA text performance will suffer if it can't move
that offscreen.

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

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