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Date: Wed, 14 Nov 2012 13:37:43 -0500
From: Rik van Riel <riel@redhat.com>
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To: Ingo Molnar <mingo@kernel.org>
CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Paul Turner <pjt@google.com>,
        Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
        Christoph Lameter <cl@linux.com>, Mel Gorman <mgorman@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Thomas Gleixner <tglx@linutronix.de>, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 1/2] sched, numa, mm: Count WS scanning against present
 PTEs, not virtual memory ranges
References: <1352883029-7885-1-git-send-email-mingo@kernel.org> <1352883029-7885-2-git-send-email-mingo@kernel.org>
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On 11/14/2012 03:50 AM, Ingo Molnar wrote:
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
>
> By accounting against the present PTEs, scanning speed reflects the
> actual present (mapped) memory.
>
> For this we modify mm/mprotect.c::change_protection() to return the
> number of ptes modified. (No change in functionality.)

We need to figure out what we actually want here.

Do we want to mark 256MB as non-present, or do we want to leave
behind 256MB of non-present (NUMA) memory? :)

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