Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932633Ab3CVDyE (ORCPT ); Thu, 21 Mar 2013 23:54:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12323 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932376Ab3CVDyB (ORCPT ); Thu, 21 Mar 2013 23:54:01 -0400 Message-ID: <514BD56F.6050709@redhat.com> Date: Thu, 21 Mar 2013 23:52:15 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Will Huck CC: Johannes Weiner , Mel Gorman , Linux-MM , Jiri Slaby , Valdis Kletnieks , Zlatko Calusic , dormando , Satoru Moriya , Michal Hocko , LKML Subject: Re: [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims at each priority References: <1363525456-10448-1-git-send-email-mgorman@suse.de> <1363525456-10448-2-git-send-email-mgorman@suse.de> <20130321155705.GA27848@cmpxchg.org> <514BA04D.2090002@gmail.com> In-Reply-To: <514BA04D.2090002@gmail.com> Content-Type: text/plain; charset=UTF-8; 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: 1349 Lines: 36 On 03/21/2013 08:05 PM, Will Huck wrote: > One offline question, how to understand this in function balance_pgdat: > /* > * Do some background aging of the anon list, to give > * pages a chance to be referenced before reclaiming. > */ > age_acitve_anon(zone, &sc); The anon lrus use a two-handed clock algorithm. New anonymous pages start off on the active anon list. Older anonymous pages get moved to the inactive anon list. If they get referenced before they reach the end of the inactive anon list, they get moved back to the active list. If we need to swap something out and find a non-referenced page at the end of the inactive anon list, we will swap it out. In order to make good pageout decisions, pages need to stay on the inactive anon list for a longer time, so they have plenty of time to get referenced, before the reclaim code looks at them. To achieve that, we will move some active anon pages to the inactive anon list even when we do not want to swap anything out - as long as the inactive anon list is below its target size. Does that make sense? -- All rights reversed -- 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/