Bug#583653: xserver-xorg-video-radeon: 15x-slower performance regression in KMS mode for 2D operations

[Michel Dänzer]

On Sam, 2010-05-29 at 15:02 +0200, Sylvain Beucler wrote: 
> On Sat, May 29, 2010 at 01:05:36PM +0200, Michel Dänzer wrote:
> > On Sam, 2010-05-29 at 10:21 +0200, Sylvain Beucler wrote: 
> > > 
> > > The attached simple test runs at 17FPS in KMS mode on my computer,
> > > against 300FPS in non-KMS mode.
> > 
> > Forgot to mention: sysprof or oprofile profiles of slow and fast runs
> > might be interesting, at least if the CPU is pegged during the runs.
> 
> Here are 2 sysprof runs:
> - UMS / fast:
>   - kernel 11.25%
>   - X 77.20%
> - KMS / slow:
>   - kernel 90.28%
>   - X 5.79%

Unfortunately, there's no information about where in the kernel the
cycles are burnt. This information should be available with sysprof
1.1.x and a kernel with the performance counter/event framework.

Anyway, this probably means it's an issue in the kernel, not the X
driver. May be solved already in newer kernels, there have been some AGP
performance improvements which I'm not sure have made it into Debian's
2.6.32 DRM backport.


> You'll have to guide me for oprofile, in particular I don't know what
> kind of kernel image I can feed it with.

I said 'sysprof or oprofile', the former is usually preferable.


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer