From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757332AbYIDINZ (ORCPT ); Thu, 4 Sep 2008 04:13:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757259AbYIDINB (ORCPT ); Thu, 4 Sep 2008 04:13:01 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:51336 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756822AbYIDIM6 (ORCPT ); Thu, 4 Sep 2008 04:12:58 -0400 Date: Thu, 04 Sep 2008 17:11:38 +0900 From: KOSAKI Motohiro To: Christoph Lameter Subject: Re: [PATCH 4/4] capture pages freed during direct reclaim for allocation by the reclaimer Cc: kosaki.motohiro@jp.fujitsu.com, Andy Whitcroft , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman In-Reply-To: <48BEFAF9.3030006@linux-foundation.org> References: <1220475206-23684-1-git-send-email-apw@shadowen.org> <48BEFAF9.3030006@linux-foundation.org> Message-Id: <20080904170016.B265.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.42 [ja] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Cristoph > How does page allocator fastpath behavior fare with this pathch? Don't worry it because 1. shrink_zone() isn't fastpath because any reclaim isn't fastpath. 2. buddy combining on __free_one_page() isn't fastpath because any buddy combining isn't fastpath. (*) (*) all modern allocator have delayed buddy combining mecanism because buddy combining increase cache miss. (please imazine address X+1 is freed when address X is cold. combining cause next alloc get address X, then caller see cold page) at least, allocator's fastpath should avoid its combining IMHO. Unfortunately the linux buddy's one is limited because zone->pcp only cache order-0 page. Then, higher order pages's free always use slow path now. but it isn't his patch failure.