Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751995AbbFZLWT (ORCPT ); Fri, 26 Jun 2015 07:22:19 -0400 Received: from cantor2.suse.de ([195.135.220.15]:52301 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751719AbbFZLWK (ORCPT ); Fri, 26 Jun 2015 07:22:10 -0400 Message-ID: <558D35DF.8080008@suse.cz> Date: Fri, 26 Jun 2015 13:22:07 +0200 From: Vlastimil Babka User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Joonsoo Kim CC: Mel Gorman , Joonsoo Kim , Andrew Morton , LKML , Linux Memory Management List , Rik van Riel , David Rientjes , Minchan Kim Subject: Re: [RFC PATCH 00/10] redesign compaction algorithm References: <1435193121-25880-1-git-send-email-iamjoonsoo.kim@lge.com> <20150625110314.GJ11809@suse.de> <20150625172550.GA26927@suse.de> <558C4EF0.2010603@suse.cz> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1520 Lines: 34 On 06/26/2015 04:14 AM, Joonsoo Kim wrote: > 2015-06-26 3:56 GMT+09:00 Vlastimil Babka : >>> on non-movable would be maintained so fallback doesn't happen. >> >> There's nothing that guarantees that the migration scanner will be emptying >> unmovable pageblock, or am I missing something? > > As replied to Mel's comment, as number of unmovable pageblocks, which is > filled by movable pages due to this compaction change increases, > possible candidate reclaimable/migratable pages from them also increase. > So, at some time, amount of used page by free scanner and amount of > migrated page by migration scanner would be balanced. > >> Worse, those pageblocks would be >> marked to skip by the free scanner if it isolated free pages from them, so >> migration scanner would skip them. > > Yes, but, next iteration will move out movable pages from that pageblock > and freed pages will be used for further unmovable allocation. > So, in the long term, this doesn't make much more fragmentation. Theoretically, maybe. I guess there's not much point discussing it further, until there's data from experiments evaluating the long-term fragmentation (think of e.g. the number of mixed pageblocks you already checked in different experiments). > Thanks. > -- 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/