From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 04 Sep 2008 17:11:38 +0900 From: KOSAKI Motohiro Subject: Re: [PATCH 4/4] capture pages freed during direct reclaim for allocation by the reclaimer 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 Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: kosaki.motohiro@jp.fujitsu.com, Andy Whitcroft , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman List-ID: 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. -- 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