Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754515AbcKIXxV convert rfc822-to-8bit (ORCPT ); Wed, 9 Nov 2016 18:53:21 -0500 Received: from TYO201.gate.nec.co.jp ([210.143.35.51]:43660 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752AbcKIXxU (ORCPT ); Wed, 9 Nov 2016 18:53:20 -0500 From: Naoya Horiguchi To: Anshuman Khandual CC: "linux-mm@kvack.org" , "Kirill A. Shutemov" , Hugh Dickins , "Andrew Morton" , Dave Hansen , Andrea Arcangeli , Mel Gorman , Michal Hocko , "Vlastimil Babka" , Pavel Emelyanov , Zi Yan , Balbir Singh , "linux-kernel@vger.kernel.org" , "Naoya Horiguchi" Subject: Re: [PATCH v2 00/12] mm: page migration enhancement for thp Thread-Topic: [PATCH v2 00/12] mm: page migration enhancement for thp Thread-Index: AQHSOVAK6wj8CPCOIkad3aMzBQ1vK6DP384AgADfVAA= Date: Wed, 9 Nov 2016 23:52:25 +0000 Message-ID: <20161109235223.GA31285@hori1.linux.bs1.fc.nec.co.jp> References: <1478561517-4317-1-git-send-email-n-horiguchi@ah.jp.nec.com> <5822FB60.5040905@linux.vnet.ibm.com> In-Reply-To: <5822FB60.5040905@linux.vnet.ibm.com> Accept-Language: en-US, ja-JP Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.128.101.4] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <8D6B989798C35F4BA47BC60D561EFF77@gisp.nec.co.jp> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1723 Lines: 46 Hi Anshuman, On Wed, Nov 09, 2016 at 04:03:04PM +0530, Anshuman Khandual wrote: > On 11/08/2016 05:01 AM, Naoya Horiguchi wrote: > > Hi everyone, > > > > I've updated thp migration patches for v4.9-rc2-mmotm-2016-10-27-18-27 > > with feedbacks for ver.1. > > > > General description (no change since ver.1) > > =========================================== > > > > This patchset enhances page migration functionality to handle thp migration > > for various page migration's callers: > > - mbind(2) > > - move_pages(2) > > - migrate_pages(2) > > - cgroup/cpuset migration > > - memory hotremove > > - soft offline > > > > The main benefit is that we can avoid unnecessary thp splits, which helps us > > avoid performance decrease when your applications handles NUMA optimization on > > their own. > > > > The implementation is similar to that of normal page migration, the key point > > is that we modify a pmd to a pmd migration entry in swap-entry like format. > > Will it be better to have new THP_MIGRATE_SUCCESS and THP_MIGRATE_FAIL > VM events to capture how many times the migration worked without first > splitting the huge page and how many time it did not work ? Thank you for the suggestion. I think that's helpful, so will try it in next version. > Also do you > have a test case which demonstrates this THP migration and kind of shows > its better than the present split and move method ? I don't have test cases which compare thp migration and split-then-migration with some numbers. Maybe measuring/comparing the overhead of migration is a good start point, although I think the real benefit of thp migration comes from workload "after migration" by avoiding thp split. Thanks, Naoya Horiguchi