Xgl - Round two

[Roland Scheidegger]

morgoth6 at box43.pl wrote:
> Hell[o]
> 
> OK, with latest glitz and Mesa snaps from CVS I was able to run Xgl 
> with much better performance. But I see some problems here, maybe all
>  of them are already know. maybe no.
> 
> 1. First thing I was unable to start Xgl server with resolution 
> bigger than 1024x768, normaly I work on 1280x1024 but when I try to 
> use it I get only 'No screens found' error. Finaly I use driconf 
> utility and enabl;e 'support larger textures' This makes possible to 
> run Xgl in 1280x1024.
> 
> I am a bit soprised because my card has 128MB of memory (Radeon 9000)
>  I wonder is this normal or it's some kind of bug ?
Not really. The problem is, the card simply has not enough memory to be
able to support larger than 1024x1024 textures in the worst case (that
is, 6 2048x2048 textures with mipmaps, 32bit need around 126MB which
won't fit along the render buffers - probably still doesn't fit if you
use the default 4 textures support). In that case you'd get (an
incredibly slow) raster fallback. That said, some dri drivers just
announce the maximum texture sizes anyway (as well as commercial
drivers), maybe it should be the default behaviour.
I'm not sure, would it be possible instead of relying on big textures to
break them up into several smaller ones? After all, you could have
resolutions larger than the hw limits for texturing (which is 2048 on
most radeons, only x800 (but not x600, x700) and x1xxx series seem to
support 4096).

> Anyway I wonder is there any other option worth to enable/disable in 
> driconf to get some boost in speed or/and stability ?
I don't think there are options worth for the needs of Xgl. Color tiling
(which is a xorg.conf option) should make a difference.

> 2. Xgl runs only in 24 (32) color depth. When I try to use 16bit (I 
> hoped 16bit would be a bit faster) I get only some ugly looking pink 
> mess on the screen.
I suppose Xgl needs the alpha channel, which you don't get with 16bit
color depth (I'd think though you shouldn't just get a mess).

> 3. The speed on 1280x1024 is realy low. At last it's several times 
> faster than my previous try, but still dead slow. Also there is 
> several corruptions for example in gnome-terminal and in Firefox. I 
> wonder also is any of the Radeon driver option can make it faster ? 
> For example EXA or something.
exa would make sense I guess. You should just try it :-).

> Should I report any of the problems to bugzilla or all of them are 
> already know ?

Roland