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Date: Mon, 15 Nov 2010 15:07:39 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Christoph Lameter <cl@linux.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Eric Dumazet <eric.dumazet@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Ingo Molnar <mingo@elte.hu>, Andi Kleen <andi@firstfloor.org>,
        Nick Piggin <npiggin@kernel.dk>
Subject: Re: [PATCH] atomic: add atomic_inc_not_zero_hint()
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On Mon, Nov 15, 2010 at 07:57:10AM -0600, Christoph Lameter wrote:
> On Sat, 13 Nov 2010, Paul E. McKenney wrote:
> 
> > On Fri, Nov 12, 2010 at 01:14:12PM -0600, Christoph Lameter wrote:
> > >
> > > prefetchw() would be too much overhead?
> >
> > No idea.  Where do you believe that prefetchw() should be added?
> 
> It is another way to get an exclusive cache line
> for situations like this. No need to give a hint.

prefetchw doesn't work on Intel (or rather is equivalent to prefetch), 
for Intel you always need to explicitely write to get an exclusive
line.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.