Bug#523385: xserver-xorg-core: xserver 1.6.0 eats CPU when moving windows

[Julien Cristau <jcristau@debian.org>]

On Fri, 2009-04-10 at 13:32 +0200, Yannick Roehlly wrote:
> Hi Julien,
> 
> Le Friday 10 April 2009 12:33:54 Julien Cristau, vous avez écrit :
> > What's in /proc/mtrr?
> 
> reg00: base=0x000000000 (    0MB), size= 2048MB, count=1: write-back
> 
no uncached or write-combining entries?

> > Also 'dmesg|grep mtrr'.
> 
> [ 1010.396231] mtrr: no MTRR for c0000000,10000000 found
> [ 1050.243537] mtrr: no MTRR for c0000000,10000000 found
> [11631.534653] mtrr: no MTRR for c0000000,10000000 found
> [11763.005918] mtrr: no MTRR for c0000000,1000000 found
> [12923.091164] mtrr: no MTRR for c0000000,10000000 found
> 
> Note that this machine has problems for running Xorg with two memory modules, 
> as described in this kernel bug report:
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=11103
> 
> (I've not yet done the test asked by Yinghai Lu)
> 
> But it has always worked fine with one memory module.
> 
> Do you think it may be related?

Yes.  Not having a write-combining mapping for the framebuffer is a big
fat fail.

Cheers,
Julien