Re: [RFC][PATCH 6/8] mm: handle_speculative_fault()

[Christoph Lameter]

On Tue, 5 Jan 2010, Arjan van de Ven wrote:

> while I appreciate the goal of reducing contention on this lock...
> wouldn't step one be to remove the page zeroing from under this lock?
> that's by far (easily by 10x I would guess) the most expensive thing
> that's done under the lock, and I would expect a first order of
> contention reduction just by having the zeroing of a page not done
> under the lock...

The main issue is cacheline bouncing. mmap sem is a rw semaphore and only
held for read during a fault.

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