Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751940Ab3HFEa7 (ORCPT ); Tue, 6 Aug 2013 00:30:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52427 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751562Ab3HFEa5 (ORCPT ); Tue, 6 Aug 2013 00:30:57 -0400 Date: Tue, 06 Aug 2013 00:30:03 -0400 From: Naoya Horiguchi To: "Aneesh Kumar K.V" Cc: Andrew Morton , linux-mm@kvack.org, Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , Hillf Danton , Michal Hocko , Rik van Riel , Wanpeng Li , linux-kernel@vger.kernel.org, Naoya Horiguchi Message-ID: <1375763403-g7t50glu-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <87haf3oabh.fsf@linux.vnet.ibm.com> References: <1374728103-17468-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1374728103-17468-9-git-send-email-n-horiguchi@ah.jp.nec.com> <87k3k7q4ox.fsf@linux.vnet.ibm.com> <1375302249-scfvftrh-mutt-n-horiguchi@ah.jp.nec.com> <87vc3qvtmc.fsf@linux.vnet.ibm.com> <1375411396-bw4cbhso-mutt-n-horiguchi@ah.jp.nec.com> <87haf3oabh.fsf@linux.vnet.ibm.com> Subject: Re: [PATCH 8/8] prepare to remove /proc/sys/vm/hugepages_treat_as_movable Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Mutt-References: <87haf3oabh.fsf@linux.vnet.ibm.com> X-Mutt-Fcc: ~/Maildir/sent/ User-Agent: Mutt 1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1607 Lines: 34 On Tue, Aug 06, 2013 at 07:22:02AM +0530, Aneesh Kumar K.V wrote: > Naoya Horiguchi writes: > >> > >> Considering that we have architectures that won't support migrating > >> explicit hugepages with this patch series, is it ok to use > >> GFP_HIGHUSER_MOVABLE for hugepage allocation ? > > > > Originally this parameter was introduced to make hugepage pool on ZONE_MOVABLE. > > The benefit is that we can extend the hugepage pool more easily, > > because external fragmentation less likely happens than other zone type > > by rearranging fragmented pages with page migration/reclaim. > > > > So I think using ZONE_MOVABLE for hugepage allocation by default makes sense > > even on the architectures which don't support hugepage migration. > > But allocating hugepages from ZONE_MOVABLE means we have pages in that > zone which we can't migrate. Doesn't that impact other features like > hotplug ? Memory blocks occupied by hugepages are not removable before this patchset, whether they are from ZONE_MOVABLE or not, and the hugepage users accepted it for now. So I think this change doesn't make things worse than now. It can be more preferable to switch on/off __GFP_MOVABLE flag depending on archs without using the tunable parameter. I'm ok for this direction, but I want to do it as a separate work. Thanks, Naoya Horiguchi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/