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Date: Thu, 10 Nov 2005 13:43:12 -0800 (PST)
From: Christoph Lameter <clameter@engr.sgi.com>
To: Andrew Morton <akpm@osdl.org>
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Subject: Re: [PATCH 10/15] mm: atomic64 page counts
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On Wed, 9 Nov 2005, Andrew Morton wrote:

> > I'm quite pleased with the way it's worked out, but you were intending
> > that the 64-bit arches should get along with 32-bit counts?  Maybe.
> 
> That seems reasonsable for file pages.  For the ZERO_PAGE the count can do
> whatever it wants, because we'd never free them up.

Frequent increments and decrements on the zero page count can cause a 
bouncing cacheline that may limit performance.