From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 7 Jun 2001 17:09:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 7 Jun 2001 17:09:00 -0400 Received: from turnover.lancs.ac.uk ([148.88.17.220]:24827 "EHLO helium.chromatix.org.uk") by vger.kernel.org with ESMTP id ; Thu, 7 Jun 2001 17:08:50 -0400 Message-Id: In-Reply-To: In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 7 Jun 2001 22:08:00 +0100 To: Linus Torvalds , Marcelo Tosatti From: Jonathan Morton Subject: Re: Background scanning change on 2.4.6-pre1 Cc: lkml , linux-mm@kvack.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> > This is going to make all pages have age 0 on an idle system after some >> > time (the old code from Rik which has been replaced by this code tried to >> > avoid that) > >There's another reason why I think the patch may be ok even without any >added logic: not only does it simplify the code and remove a illogical >heuristic, but there is nothing that really says that "age 0" is >necessarily very bad. Here's my take on it. The point of ageing is twofold - to age down pages that aren't in use, and to age up pages that *are* in use. So, pages that are in use will remain with high ages even when background scanning is being done, and pages that aren't in use will decay to zero age. I can't see what's wrong with that. When we need more memory, it's a Very Good Thing to know that most of the pages in the system haven't been accessed in yonks - we know exactly which ones we want to throw out first. -------------------------------------------------------------- from: Jonathan "Chromatix" Morton mail: chromi@cyberspace.org (not for attachments) The key to knowledge is not to rely on people to teach you it. GCS$/E/S dpu(!) s:- a20 C+++ UL++ P L+++ E W+ N- o? K? w--- O-- M++$ V? PS PE- Y+ PGP++ t- 5- X- R !tv b++ DI+++ D G e+ h+ r++ y+(*)