Re: radeon-pre-2

[Jon Smirl]

On Sat, 11 Sep 2004 17:21:22 +0100, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxx
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