From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933095AbXGYP3G (ORCPT ); Wed, 25 Jul 2007 11:29:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757263AbXGYP2z (ORCPT ); Wed, 25 Jul 2007 11:28:55 -0400 Received: from mx1.redhat.com ([66.187.233.31]:37128 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757973AbXGYP2y (ORCPT ); Wed, 25 Jul 2007 11:28:54 -0400 Message-ID: <46A76C09.6000602@redhat.com> Date: Wed, 25 Jul 2007 11:28:09 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: Nick Piggin CC: Eric St-Laurent , Rusty Russell , Fengguang Wu , Dave Jones , Peter Zijlstra , linux-kernel , Andrew Morton , Tim Pepper , Chris Snook Subject: Re: [PATCH 0/3] readahead drop behind and size adjustment References: <20070721210005.000228000@chello.nl> <20070722023923.GA6438@mail.ustc.edu.cn> <20070722024428.GA724@redhat.com> <20070722081010.GA6317@mail.ustc.edu.cn> <1185093236.6344.87.camel@localhost.localdomain> <46A46E4B.7050007@yahoo.com.au> <1185338106.7105.44.camel@perkele> <46A6DD7F.1050505@yahoo.com.au> In-Reply-To: <46A6DD7F.1050505@yahoo.com.au> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nick Piggin wrote: > What *I* think is supposed to happen is that newly read in pages get > put on the inactive list, and unless they get accessed againbefore > being reclaimed, they are allowed to fall off the end of the list > without disturbing active data too much. > > I think there is a missing piece here, that we used to ease the reclaim > pressure off the active list when the inactive list grows relatively > much larger than it (which could indicate a lot of use-once pages in > the system). > > Andrew got rid of that logic for some reason which I don't know, but I > can't see that use-once would be terribly effective today (so your > results don't surprise me too much). I suspect that reason is that use-once works great for page cache pages, but anonymous pages share the same LRUs and need a more balanced aging approach. The result: an LRU list that works ok for both types of pages most of the time, but falls over in some workloads. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic.