9.1 Proposal: Top five performance problems

[Erik Garrison]

On Fri, Oct 24, 2008 at 6:36 PM, Jordan Crouse <jordan.crouse at amd.com> wrote:
> On 25/10/08 00:00 +0200, NoiseEHC wrote:
>> The Geode X drive copyes every bit of data to the command ring buffer by
>> using the CPU so that is sure that those "almost no CPU cycles" thing is
>> at least a bit stretch... :) According to Jordan Crouse it will not be
>> better but he was not too concrete so in the end I am not sure what he
>> was really talking about, see:
>> http://lists.laptop.org/pipermail/devel/2008-May/014797.html
>
> Indeed - many CPU cycles are used during compositing.  There is a lot of
> math that happens to generate the masks and other collateral to render
> the alpha icon on the screen.  The performance savings in the composite
> code comes from not having to read video memory to get the src pixel
> for the alpha operation(s).  That performance savings is already available
> in the X driver today.

Ah!

So what work needs to be done to realize these performance savings?
Or are you saying that we can already getting them by using composite?
 Or by another method?

Also, here:

> The performance savings in the composite
> code comes from not having to read video memory to get the src pixel
> for the alpha operation(s).

Do you mean "not having to generate the video memory to get the src
pixel"?  By not asking applications to redraw themselves aren't we
saving CPU cycles?

Erik