[PATCH] Ensure blitter quiescience before reading pixels from the framebuffer

Michel Dänzer michel at tungstengraphics.com
Mon Jul 30 06:58:16 PDT 2007

On Mon, 2007-07-30 at 14:02 +0200, Bernardo Innocenti wrote:
> Michel Dänzer wrote:
> > Not sure there's still anyone around who cares about XAA...
> afaik, as of today XAA is still the default on all mayor Linux
> distros.  Simple bug fixes are probably still wanted.

So are you volunteering to maintain XAA? :)

> >> Moreover, we're just scratching the surface of serious performance
> >> bottlenecks in both EXA and XAA.  Is anyone interested in discussing
> >> possible solutions?
> > 
> > I certainly am for EXA.
> I'm unsure how we could eliminate those 1x1 pixmaps used for solid fills,
> but they're certainly a big performance hit.  In some cases, we even upload
> them to the framebuffer by *dma*, then read the pixel with CPU :-)

Adam Jackson fixed that in GIT.

> A half-way solution would involve teaching the server-side to recognize these
> degenerate cases early and throw away the picture.  This would still require
> changes in the interface between EXA and the drivers.

If there's still a measurable penalty in some cases with the above
change, this is probably the way to go.

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

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