Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755003Ab1D0Ilv (ORCPT ); Wed, 27 Apr 2011 04:41:51 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:55215 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754843Ab1D0Ild (ORCPT ); Wed, 27 Apr 2011 04:41:33 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 27 Apr 2011 17:34:50 +0900 From: KAMEZAWA Hiroyuki To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , Christoph Lameter , Johannes Weiner , KOSAKI Motohiro , Mel Gorman , Rik van Riel , Andrea Arcangeli Subject: Re: [RFC 6/8] In order putback lru core Message-Id: <20110427173450.82cef21e.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <51e7412097fa62f86656c77c1934e3eb96d5eef6.1303833417.git.minchan.kim@gmail.com> References: <51e7412097fa62f86656c77c1934e3eb96d5eef6.1303833417.git.minchan.kim@gmail.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.1.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1955 Lines: 49 On Wed, 27 Apr 2011 01:25:23 +0900 Minchan Kim wrote: > This patch defines new APIs to putback the page into previous position of LRU. > The idea is simple. > > When we try to putback the page into lru list and if friends(prev, next) of the pages > still is nearest neighbor, we can insert isolated page into prev's next instead of > head of LRU list. So it keeps LRU history without losing the LRU information. > > Before : > LRU POV : H - P1 - P2 - P3 - P4 -T > > Isolate P3 : > LRU POV : H - P1 - P2 - P4 - T > > Putback P3 : > if (P2->next == P4) > putback(P3, P2); > So, > LRU POV : H - P1 - P2 - P3 - P4 -T > > For implement, we defines new structure pages_lru which remebers > both lru friend pages of isolated one and handling functions. > > But this approach has a problem on contiguous pages. > In this case, my idea can not work since friend pages are isolated, too. > It means prev_page->next == next_page always is false and both pages are not > LRU any more at that time. It's pointed out by Rik at LSF/MM summit. > So for solving the problem, I can change the idea. > I think we don't need both friend(prev, next) pages relation but > just consider either prev or next page that it is still same LRU. > Worset case in this approach, prev or next page is free and allocate new > so it's in head of LRU and our isolated page is located on next of head. > But it's almost same situation with current problem. So it doesn't make worse > than now and it would be rare. But in this version, I implement based on idea > discussed at LSF/MM. If my new idea makes sense, I will change it. > I think using only 'next'(prev?) pointer will be enough. Thanks, -Kame -- 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/