Re: [xougen] Arch specific optimizations [XAA]

[Alan Cox]

On Llu, 2003-09-08 at 16:44, emmanuel ALLAUD wrote:
> So basically you think that the only real improvment
> would be done by adding hardware acceleration support
> to some core functions of XRender (I have seen
> messages on XFree-devel from someone who is doing that
> though I don't know how advanced he is now).

Once you can do DMA fetch of tiles of video screen (reading them
with the CPU is really slow) then every last clock you can ring
out of the software renderer will be worth it for stuff you can't
directly perform on the video card itself.

Currently you should be able to use the vesa unaccelerated driver
with shadowfb to write hand tuned Xrender functions for unaccel
cards and that doesn't need to wait for other stuff. (In the
vesa/shadowfb case your render buffer to read is main memory so
the performance issue is gone and you can just fix the render
code to be fast).