Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751970AbcDKH1I (ORCPT ); Mon, 11 Apr 2016 03:27:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:35447 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751026AbcDKH1G (ORCPT ); Mon, 11 Apr 2016 03:27:06 -0400 Subject: Re: [PATCH v2 4/4] mm, compaction: direct freepage allocation for async direct compaction To: Joonsoo Kim References: <1459414236-9219-1-git-send-email-vbabka@suse.cz> <1459414236-9219-5-git-send-email-vbabka@suse.cz> <20160411071351.GB26116@js1304-P5Q-DELUXE> Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Rik van Riel , David Rientjes , Minchan Kim , Michal Hocko From: Vlastimil Babka Message-ID: <570B51C6.4050005@suse.cz> Date: Mon, 11 Apr 2016 09:27:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <20160411071351.GB26116@js1304-P5Q-DELUXE> Content-Type: text/plain; charset=windows-1252; 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: 790 Lines: 14 On 04/11/2016 09:13 AM, Joonsoo Kim wrote: > 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. > > If we fails migration, free pages will remain and they can interfere > further compaction success because they doesn't come from previous > order-aligned block but can come from next order-aligned block. You > need to free remaining freelist after migration attempt fails? Oh, good point, thanks!