Message-ID: <4FC4D58A.50800@redhat.com>
Date: Tue, 29 May 2012 09:56:26 -0400
From: Rik van Riel <riel@redhat.com>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Andrea Arcangeli <aarcange@redhat.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Hillf Danton <dhillf@gmail.com>,
        Dan Smith <danms@us.ibm.com>,
        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>
Subject: Re: [PATCH 13/35] autonuma: add page structure fields
References: <1337965359-29725-1-git-send-email-aarcange@redhat.com>  <1337965359-29725-14-git-send-email-aarcange@redhat.com> <1338297385.26856.74.camel@twins>
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On 05/29/2012 09:16 AM, Peter Zijlstra wrote:
> On Fri, 2012-05-25 at 19:02 +0200, Andrea Arcangeli wrote:

> 24 bytes per page.. or ~0.6% of memory gone. This is far too great a
> price to pay.
>
> At LSF/MM Rik already suggested you limit the number of pages that can
> be migrated concurrently and use this to move the extra list_head out of
> struct page and into a smaller amount of extra structures, reducing the
> total overhead.

For THP, we should be able to track this NUMA info on a
2MB page granularity.

It is not like we will ever want to break up a large
page into small pages anyway (with different 4kB pages
going to different NUMA nodes), because the THP benefit
is on the same order of magnitude as the NUMA benefit.

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