From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx180.postini.com [74.125.245.180]) by kanga.kvack.org (Postfix) with SMTP id 2874B6B0031 for ; Tue, 6 Aug 2013 00:30:44 -0400 (EDT) Date: Tue, 06 Aug 2013 00:30:03 -0400 From: 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 Sender: owner-linux-mm@kvack.org List-ID: 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 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org