From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f49.google.com (mail-lf0-f49.google.com [209.85.215.49]) by kanga.kvack.org (Postfix) with ESMTP id 51D8D6B0005 for ; Mon, 4 Apr 2016 05:32:03 -0400 (EDT) Received: by mail-lf0-f49.google.com with SMTP id c62so160703027lfc.1 for ; Mon, 04 Apr 2016 02:32:03 -0700 (PDT) Received: from outbound-smtp02.blacknight.com (outbound-smtp02.blacknight.com. [81.17.249.8]) by mx.google.com with ESMTPS id x3si27335461wjy.198.2016.04.04.02.32.01 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 04 Apr 2016 02:32:01 -0700 (PDT) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp02.blacknight.com (Postfix) with ESMTPS id 426B79909F for ; Mon, 4 Apr 2016 09:32:01 +0000 (UTC) Date: Mon, 4 Apr 2016 10:31:59 +0100 From: Mel Gorman Subject: Re: [PATCH v2 4/4] mm, compaction: direct freepage allocation for async direct compaction Message-ID: <20160404093159.GB4773@techsingularity.net> References: <1459414236-9219-1-git-send-email-vbabka@suse.cz> <1459414236-9219-5-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1459414236-9219-5-git-send-email-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Rik van Riel , David Rientjes , Minchan Kim , Michal Hocko On Thu, Mar 31, 2016 at 10:50:36AM +0200, Vlastimil Babka wrote: > The goal of direct compaction is to quickly make a high-order page available > for the pending allocation. The free page scanner can add significant latency > when searching for migration targets, although to succeed the compaction, the > only important limit on the target free pages is that they must not come from > the same order-aligned block as the migrated pages. > What prevents the free pages being allocated from behind the migration scanner? Having compaction abort when the scanners meet misses compaction opportunities but it avoids the problem of Compactor A using pageblock X as a migration target and Compactor B using pageblock X as a migration source. -- Mel Gorman SUSE Labs -- 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