Re: radeon-pre-2

Jon Smirl
2004-09-11T17:34:09Z

On Sat, 11 Sep 2004 17:21:22 +0100, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Sad, 2004-09-11 at 17:46, Jon Smirl wrote:
> > User 1's game queues up 20ms of 3D drawing commands.
> > Process swap to user 2. ->quiesce() is going to take 20ms.
> > User 2's timeslice expires and we go back to user 1.
> > User 1 queues up another 20ms.
> >
> > User 2's editor is never going to function.
>
> If you implement it wrongly sure. If you implemented it right then
> this occurs.
>
> User 1 queues 20 ms of 3D commands
> User 1 is pre-empted
> User 2 wants the 2D engine
> User 2 beings wait for 2D
> User 2 sleeps
> User 1 wakes
> User 1 beings wait for 3D but discovers a claim is in progress
> User 1 sleeps
> User 2 wakes, runs commands

This model destroys the parallel processing between the main CPU and the GPU.

>
> If you have DRI loaded then as you rightly say the obvious desired
> outcome is that the fb engine either turns acceleration off or switches
> to using the DRI layer.
>
> But this is a pretty obscure case, and one we can't even begin to
> support yet anyway.
>
>

--
Jon Smirl
jonsmirl@gmail.com