ATI 6.12.4 on ultraSparc runs slow

[Dave Airlie]

On Thu, Mar 25, 2010 at 8:05 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
> 2010/3/24 jean-francois simon <jfsimoncasa at gmail.com>:
>>
>> 2010/3/24 Michel Dänzer <michel at daenzer.net>
>>>
>>> > so it is PIO not DMA? just curious, where is the code that is doing
>>> > that transfer?
>>>
>>> shadowUpdatePacked() in xserver/miext/shadow/shpacked.c .
>>>
>>>
>> very interesting thanks.
>> i can see that this transfer is being triggered by something called  the
>> shadow block handler. and i am thinking maybe this is not done often enough,
>> thus explaning the slow videos?
>
> More likely the write to vram performance is better on x86 since you
> are using write combining.

Yes definitely this, most non-x86 CPUs don't have mtrr/write combining support,
which really helps for shadowfb situations. The only thing I can think
to do is possible
some sparc specific optimisations to the copying that may or may not
speed it up.

I know Linux/sparc has mostly working DRM, since davem plays quake3 on his.

Dave.