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

[Dan Amelang]

On 8/3/07, Bernardo Innocenti <bernie at codewiz.org> wrote:
>
> We're considering switching to 24bit (32bpp) because format conversions
> are expensive and Cairo works mostly with a8r8b8g8.
>
> The downside is that we waste double as much video memory and simple
> operations such as fills and copies instantly become 2x slower.

At the X dev conference next month, I'll be presenting jitblt, which
might solve your slow 16bpp problem. It's basically a pixman "backend"
that JIT compiles specialized fast paths for any given format. Since
both cairo and X use pixman for software compositing, jitblt-pixman
should get you a boost across the board.

I'll be visiting the OLPC offices later this month, so I can bring a
jitblt-enabled OLPC with me if you or Jim or whoever might be
interested.

Dan