Mittwoch, 18. März 2009

UXA ... unuseable slow

I just recently filed a bug about horrible performance when runnig the existing X11 pipeline using intel's forked UXA accaleration architecture. AWT applications are extremly slow, hardly useable.

> We don't intend to fix this in UXA ourselves. If you're drawing unantialiased
> text in 2009, your software fails. If you're not using Xft or cairo for text
> drawing in 2009, your software fails even harder (it would perform fine if you
> were).

So, it seems intel doesn't care they broke your software :-/

Donnerstag, 5. März 2009

Shader Trapezoids

Lately I've been playing with shaders a bit, investigating the possibility of implementing XRender's more complex features (trapezoids and gradients) using shaders instead of falling back to software all the time.

I started with trapezoids because they're used a lot, and because pixman's strange implementation made me curious:

I used NVidia's Cg language because it can be compiled down to ARG_fragment_program, which is the best my i945GM can do. Performance could be better and I am limited to 0,25px subpixel precision because of the i915's 64 ALU instruction limit.
But at least from what I can tell the traps should conform to the spec for imprecise trapezoid mode (default), I'll try to feed some cairo output at it and see what will go wrong ;)

On my i945GM I get 25fps fullscreen, a RedeonHD3850 is able to do ~1000fps and is still not ALU limited :)

Hopefully some day that stuff will find its way into one of the opensource drivers, I guess on more powerful hardware like AMD's R600/700 GPU setup costs will dominate :)