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Date: Wed, 25 Feb 2009 13:33:07 -0500 (EST)
From: Christoph Lameter <cl@linux-foundation.org>
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To: Mel Gorman <mel@csn.ul.ie>
cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
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       ming.m.lin@intel.com, yanmin_zhang@linux.intel.com
Subject: Re: [PATCH 20/20] Get rid of the concept of hot/cold page freeing
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On Wed, 25 Feb 2009, Mel Gorman wrote:

> It'd impact it for sure. Due to the non-temporal stores, I'm surprised
> there is any measurable impact from the patch.  This has likely been the
> case since commit 0812a579c92fefa57506821fa08e90f47cb6dbdd. My reading of
> this (someone correct/enlighten) is that even if the data was cache hot,
> it is pushed out as a result of the non-temporal access.

A nontemporal store simply does not set the used flag for the cacheline.
So the cpu cache LRU will evict the cacheline sooner. Thats at least how
it works on I64.