FYI: XBMC is slow on Xpress 1250, fast on X1650 PRO

[Alex Deucher]

On Mon, May 24, 2010 at 2:55 PM, Toan <nguyenthetoan at gmail.com> wrote:
> Hi
>
> I have a ASUS M2V-HDMI motherboard with internal ATI Xpress 1250,
> and a PCI-E ATI X1650 PRO card. I use it as Home Theater System
> with XBMC software. I use Ubuntu 10.04, with xorg-edger PPA
> repository.
>
> If I use the Xpress 1250 graphic card, XBMC is very slow (~10-15 fps).
> On the other hand, XBMC on ATI X1650 PRO gives 70-90 fps. FPS for
> glxgears, however, are quite similar on both).
>
> For obvious reasons (less noise, less power consumption, direct HDMI
> output), I prefer to use the internal Xpress 1250 card if possible.
> I don't know if I setup it wrong (wrong options,....) or is it because
> of the open source radeon driver is much better for X1650 than X1250
> at the moment. If anyone could help me with this, i'll greatly
> appreciate it. I'd happy to send you all the logs, ....

The x1250 (r4xx-based 3D) and x1650 (r5xx-based 3D) have very similar
3D engines.  Most likely XBMC is making heavy use of vertex shaders.
The x1250 does not have vertex shader hardware while the x1650 does.
A better software vertex shader compiler can make big difference.
Eventually you'll see better performance once the r300 gallium driver
takes advantage of the llvm vertex shader work.

Alex