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

[Andi Kleen]

On Tue, Jan 05, 2010 at 11:47:49AM -0600, Christoph Lameter wrote:
> On Tue, 5 Jan 2010, Andi Kleen wrote:
> 
> > > Oh well. Somebody who is bored might look at trying to make the wrapper
> > > code in arch/x86/lib/semaphore_32.S work on x86-64 too. It should make the
> > > successful rwsem cases much faster.
> >
> > Maybe, maybe not.
> 
> What we saw in the past was that the cost of acquiring exclusive
> access to the contended cachelines containing mmap_sem and rss counters
> was most important.

That cost should be about the same between the spinlock and the atomic version.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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