Composite really slow

[Alex Deucher]

On Sun, 21 Nov 2004 21:49:43 +0100, Jakub Piotr Cłapa <loc at toya.net.pl> wrote:
> Alex Deucher wrote:
> 
> 
> > On Tue, 16 Nov 2004 10:43:02 -0600, Evan K. Langlois
> > <evan at coolrunningconcepts.com> wrote:
> >
> >>Hi Everyone,
> >>
> >>It could be my imagination, but it seems that the Composite extension is
> >>much slower in Xorg than in the freedesktop.org/kdrive combination.
> >>Even with xcompmgr off, I have issues if Composite is in the config
> >>file.
> >>
> >>I've tried lowering my screen resolution and reducing color depth, which
> >>helps minimally, and if lowered enough I can compare the freedesktop.org
> >>X server with Xorg, and while Xorg is more correct in its output, it
> >>should be MUCH faster than kdrive based servers.  Its not.  It performs
> >>as expected with Composite turned off, but the freedesktop.org X server
> >>is plenty fast with this feature, and xcompmgr can be run (normally off
> >>when I run Xorg) and even with shadows and fade effects its faster than
> >>Xorg without the features (and Composite turned on).
> >>
> >>I'm using the Radeon driver that ships with Xorg (not the binary) with
> >>an ATI Radeon 9200SE with 128MB of RAM.  In my normal 1600x1200x24 bit
> >>its night and day.  I'm wondering if Xorg is using my slower desktop RAM
> >>(only 256MB and PC100 on a K6-2/550) for the off-screen bitmaps instead
> >>of the 128MB on the card.  With Composite enabled, X uses nearly all the
> >>CPU and apps suffer badly.  With it turned off, its quite snappy and
> >>very useable.
> >>
> >>Ideas?  I can post my Xorg if someone wants it but until then, I won't
> >>waste the bandwidth as I have wacom drivers and all sorts of stuff in
> >>there, so its kinda long.
> >
> > Xorg is much slower than kdrive when it comes to composite and render
> > acceleration.  The problem is XAA (the acceleration architecture in
> > Xorg) does not lend it self as well to accelerating these extensions
> > as KAA (the acceleration architecture in kdrive).  Kdrive accelerates
> > more of what is needed for composite so composite is faster on Kdrive.
> 
> And when can we expect some improvements here? It should be possible to
> improve the open source drivers at least...
> 

It's all open source.  Someone just needs to find the time to port KAA
and the related driver bits to xorg.  Unfortunately, it's not a
trivial task.

Alex

> --
> Regards,
> Jakub Piotr Cłapa
> 
>