Re: radeon-pre-2

Vladimir Dergachev
2004-09-13T15:07:29Z

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On Sun, 12 Sep 2004, Michel [ISO-8859-1] Dänzer wrote:

> On Sun, 2004-09-12 at 20:45 -0400, Vladimir Dergachev wrote:
>>
>> On Sun, 12 Sep 2004, Michel [ISO-8859-1] Dnzer wrote:
>>
>>> On Sun, 2004-09-12 at 23:42 +0100, Dave Airlie wrote:
>>>>
>>>> I think yourself and Linus's ideas for a locking scheme look good, I also
>>>> know they won't please Jon too much as he can see where the potential
>>>> ineffecienes with saving/restore card state on driver swap are, especailly
>>>> on running fbcon and X on a dual-head card with different users.
>>>
>>> Frankly, I don't understand the fuss about that. When you run a 3D
>>> client on X today, 3D client and X server share the accelerator with
>>> this scheme, and as imperfect as it is, it seems to do a pretty good job
>>> in my experience.
>>
>> Not that good - try dragging something while a DVD video is playing.
>
> What are you getting at?

The overlay window is currently using part of what is being proposed by
"multiple drivers" proponents. It has to make engine queiscent so it can
write data directly to the video memory. It does *not* have to save the
state.

So, as Jon rightly points out the "multiple drivers" scheme only makes
sense in the current usage patter - you either use X or framebuffer, never
both at the same time and you consider a few seconds per switch normal.
(Not that it actually has to take few seconds, I am just pointing out the
the expectations are well below what we do now)

However, if we want the switch from X to framebuffer to be as fast as
switching between different text consoles (assuming they have the same
resolution) and if we want to be able to run different Xservers on
different consoles or Xserver+framebuffer combinations Jon's proposal
wins.

best

Vladimir Dergachev

>
>
> --
> Earthling Michel DÃ¤nzer | Debian (powerpc), X and DRI developer
> Libre software enthusiast | http://svcs.affero.net/rm.php?r=daenzer
>