From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f177.google.com (mail-ie0-f177.google.com [209.85.223.177]) by kanga.kvack.org (Postfix) with ESMTP id 99A0D6B0035 for ; Thu, 31 Oct 2013 01:00:54 -0400 (EDT) Received: by mail-ie0-f177.google.com with SMTP id e14so3923464iej.8 for ; Wed, 30 Oct 2013 22:00:54 -0700 (PDT) Received: from psmtp.com ([74.125.245.180]) by mx.google.com with SMTP id nv6si1551558icc.80.2013.10.30.22.00.51 for ; Wed, 30 Oct 2013 22:00:52 -0700 (PDT) Received: by mail-qc0-f180.google.com with SMTP id e9so1368995qcy.25 for ; Wed, 30 Oct 2013 22:00:50 -0700 (PDT) Message-ID: <5271E3F8.80108@gmail.com> Date: Thu, 31 Oct 2013 01:00:40 -0400 From: KOSAKI Motohiro MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: kosaki.motohiro@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, KOSAKI Motohiro , Mel Gorman (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, 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