From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756066AbYKKLdx (ORCPT ); Tue, 11 Nov 2008 06:33:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755228AbYKKLdp (ORCPT ); Tue, 11 Nov 2008 06:33:45 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:58394 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754895AbYKKLdo (ORCPT ); Tue, 11 Nov 2008 06:33:44 -0500 Subject: Re: How kernel applies LRU to swap out physical pages? From: Peter Zijlstra To: KOSAKI Motohiro Cc: Pan ruochen , linux-kernel@vger.kernel.org In-Reply-To: <20081111180233.8B38.KOSAKI.MOTOHIRO@jp.fujitsu.com> References: <1226393845.7685.1294.camel@twins> <20081111180233.8B38.KOSAKI.MOTOHIRO@jp.fujitsu.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Tue, 11 Nov 2008 12:33:40 +0100 Message-Id: <1226403220.7685.1601.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2008-11-11 at 18:56 +0900, KOSAKI Motohiro wrote: > > On Tue, 2008-11-11 at 16:22 +0800, Pan ruochen wrote: > > > Hi All, > > > I'm reading the linux kernel 2.6.14. But can't understand how LRU algorithm > > > is applied to page swapping. what is the 'USED' of LRU referred to? The > > > reference counter which the page is mapped by processes, or the frequency that > > > CPU reads/writes in the page. In common sense, the LRU algorithm will be more > > > optimal for the second case. But it depends on CPU capability. > > > I will be very appreciated if somebody can explain that in details. > > > > We don't actually use LRU but something like CLOCK. FWIW in case you hadn't found it yet: http://en.wikipedia.org/wiki/Page_replacement_algorithm is a fairly decent page on the subject.