From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f172.google.com (mail-wi0-f172.google.com [209.85.212.172]) by kanga.kvack.org (Postfix) with ESMTP id 62C196B0038 for ; Fri, 26 Jun 2015 07:22:11 -0400 (EDT) Received: by wicnd19 with SMTP id nd19so42477650wic.1 for ; Fri, 26 Jun 2015 04:22:11 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id e1si57978049wjp.38.2015.06.26.04.22.09 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 26 Jun 2015 04:22:09 -0700 (PDT) Message-ID: <558D35DF.8080008@suse.cz> Date: Fri, 26 Jun 2015 13:22:07 +0200 From: Vlastimil Babka MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Mel Gorman , Joonsoo Kim , Andrew Morton , LKML , Linux Memory Management List , Rik van Riel , David Rientjes , Minchan Kim 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, 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