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Date: Mon, 02 Jul 2012 00:24:36 -0400
From: Rik van Riel <riel@redhat.com>
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Subject: Re: [PATCH 28/40] autonuma: make khugepaged pte_numa aware
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To: Andrea Arcangeli <aarcange@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hillf Danton <dhillf@gmail.com>, Dan Smith <danms@us.ibm.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>, Suresh Siddha <suresh.b.siddha@intel.com>, Mike Galbraith <efault@gmx.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Lai Jiangshan <laijs@cn.fujitsu.com>, Bharata B Rao <bharata.rao@gmail.com>, Lee Schermerhorn <Lee.Schermerhorn@hp.com>, Johannes Weiner <hannes@cmpxchg.org>, Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>, Christoph Lameter <cl@linux.com>, Alex Shi <alex.shi@intel.com>, Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Don Morris <don.morris@hp.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>

On 06/28/2012 08:56 AM, Andrea Arcangeli wrote:
> If any of the ptes that khugepaged is collapsing was a pte_numa, the
> resulting trans huge pmd will be a pmd_numa too.

Why?

If some of the ptes already got faulted in and made really
resident again, why do you want to incur a new NUMA fault
on the newly collapsed hugepage?

Is there something on we should know about?

If so, could you document it?

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