Re: [PATCH 00/25] mm: Preemptibility -v7

From: Peter Zijlstra
Date: Tue Jan 25 2011 - 16:08:50 EST


On Tue, 2011-01-25 at 12:47 -0800, Andi Kleen wrote:
>
> I thought the reason for the preempt off inside the mmu gather region was
> to stay on the same CPU for local/remote flushes. How would it change that?

afaik its been preempt-off solely because it was always inside a number
of spinlocks, I know both Hugh and BenH worked on making it preemptible
far before I started this.

I remember Hugh and Nick talking about this at OLS'06 or 07, can't
really remember.

As to local/remote flushes, there is no real saying where the pages came
from due to on-demand paging and the scheduler never having had a notion
of home-node. Therefore freeing them wouldn't be more of less local if
that is exposed to the same migration as allocation was.


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