Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752605Ab3JaFAv (ORCPT ); Thu, 31 Oct 2013 01:00:51 -0400 Received: from mail-qc0-f175.google.com ([209.85.216.175]:56110 "EHLO mail-qc0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750845Ab3JaFAu (ORCPT ); Thu, 31 Oct 2013 01:00:50 -0400 Message-ID: <5271E3F8.80108@gmail.com> Date: Thu, 31 Oct 2013 01:00:40 -0400 From: KOSAKI Motohiro User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Andrew Morton CC: kosaki.motohiro@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, KOSAKI Motohiro , Mel Gorman Subject: Re: [PATCH] mm: __rmqueue_fallback() should respect pageblock type References: <1383193489-27331-1-git-send-email-kosaki.motohiro@gmail.com> <20131030213537.f346d751.akpm@linux-foundation.org> In-Reply-To: <20131030213537.f346d751.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; 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: 1379 Lines: 31 (10/31/13 12:35 AM), Andrew Morton wrote: > On Thu, 31 Oct 2013 00:24:49 -0400 kosaki.motohiro@gmail.com wrote: > >> When __rmqueue_fallback() don't find out a free block with the same size >> of required, it splits a larger page and puts back rest peiece of the page >> to free list. >> >> But it has one serious mistake. When putting back, __rmqueue_fallback() >> always use start_migratetype if type is not CMA. However, __rmqueue_fallback() >> is only called when all of start_migratetype queue are empty. That said, >> __rmqueue_fallback always put back memory to wrong queue except >> try_to_steal_freepages() changed pageblock type (i.e. requested size is >> smaller than half of page block). Finally, antifragmentation framework >> increase fragmenation instead of decrease. >> >> Mel's original anti fragmentation do the right thing. But commit 47118af076 >> (mm: mmzone: MIGRATE_CMA migration type added) broke it. >> >> This patch restores sane and old behavior. > > What are the user-visible runtime effects of this change? Memory fragmentation may increase compaction rate. (And then system get unnecessary slow down) -- 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/