[REVIEW] DMX2 DIX merge

[Adam Jackson]

On Thu, 2010-01-07 at 14:46 -0800, Aaron Plattner wrote:
> On Thu, Jan 07, 2010 at 07:04:45AM -0800, Adam Jackson wrote:
> > On Wed, 2010-01-06 at 17:26 -0800, Keith Packard wrote:
> > > On Wed, 06 Jan 2010 17:39:15 -0500, Adam Jackson <ajax at nwnk.net> wrote:
> > > > But that's still kind of gross, since your per-screen pixmaps are still
> > > > going to end up in VRAM, and then read back out to get to the window
> > > > pixmap, and then back into VRAM for the compositor.
> > > 
> > > I don't think I get this piece -- you shouldn't ever have to touch any
> > > of the pixmaps with the CPU for compositing to work with Xinerama.
> > 
> > The DMX2 pixmap storage change is that window pixmaps for redirected
> > windows live in host memory, period.  Your XA probably tries to create
> > new pixmaps in VRAM.  Blitting from that to the window becomes a
> > readback, which I suppose could be CPU-driven or not.
> 
> That's not acceptable for us, it would be a MASSIVE performance regression.
> Does this only happen for Xinerama, or all the time?

Would only be for Xinerama.  But I should emphasize, this isn't a change
I'm planning to implement.  Pixmap storage needs to be far smarter than
simply forcing it to host memory.

- ajax
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