Performance of SheevaPlug on 8-stable

[Rafal Jaworowski]

On 2010-03-10, at 14:58, Grzegorz Bernacki wrote:

>> There are a few data dangling allocations that I would like to see
>> closed from the multiple kernel allocation fix. *IN THEORY, IF* a page
>> is allocated via the arm_nocache (DMA COHERENT) or a sendfile, then
>> it is never marked as unallocated. *IN THEORY*, if that page is used
>> again, then we could falsely believe that page is being shared and
>> we turn off the cache, eventhough it is not shared.
>> 	http://www.casselton.net/~tinguely/arm_pmap_unmanaged.diff
>> * Disclaimer: I am not sure if DMA COHERENT nor sendfiles are used in
>> the Sheeva implementation. This is a theoritical observation of a side
>> effect of the multiple kernel mapping patch that we did just before
>> FreeBSD 8-release.
> 
> I instrumented code with KTRs and your theory is correct. Kernel reuse page
> which was previouly mapped via arm_nocache. Your patch should be applied
> to -current.

Bernd,
Could you confirm this also fixes the issues for you on the RM9200 machine? If so, I'll go on and commit the changes.

Rafal