Poor compositing performance on 965Q chipset with intel 2.2.1 driver

Barry Scott barry.scott at onelan.co.uk
Fri May 9 07:59:52 PDT 2008

Keith Packard wrote:
> On Fri, 2008-05-09 at 14:11 +0100, Barry Scott wrote:
>> Using latest libpciaccess makes no difference MTRR status is the same:
> It's not the MTRRs that are broken, it's the page mapping which is
> setting the ignore cache and write through bits on each page mapped by
> libpciaccess. There's a kludge-around which takes advantage of a
> different kernel bug to clear those bits. A simple test:
> $ x11perf -shmput500
> If that gives you a number significantly less than 1000, then your pages
> are probably mis-mapped.
We see 1110 on the 965Q (1.86GHz CPU) and 1250 on the Q35 (2.33GHz CPU).

Could the problem be as simple as the driver is using different 
acceleration on the
two chips?


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