[Desktop_architects] Re: Linux desktop, the fun thread

[Jim Gettys]

On Fri, 2005-12-16 at 08:00 -0800, Linus Torvalds wrote:

> I _think_ some drivers effectively already do this when they enable direct 
> rendering. The DRI layer does have the capability, and with many (most?) 
> cards the X server actually needs to use the kernel interfaces for 2D too, 
> just because it's either fully a subset of 3D, or because they share part 
> of the command structure.

I believe the NVidia closed source drivers are "sane".  It is not based
on the broken XAA driver model.

I don't think most of the open source drivers are sane.

> 
> Of course, how well that works, I dunno. For example, at least the radeon 
> driver just does a busy-wait if the command ring fills up in the kernel, 
> so it's up to user space to make sure that it adds the proper "raise 
> interrupt" commands every once in a while, and waits for commands to 
> drain.

And so the poor Linux scheduler has no clue that X is an interactive
process, causing it to be penalized.
				- Jim