From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261904AbUFCNih (ORCPT ); Thu, 3 Jun 2004 09:38:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263616AbUFCNih (ORCPT ); Thu, 3 Jun 2004 09:38:37 -0400 Received: from mail.tmr.com ([216.238.38.203]:30478 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id S261904AbUFCNig (ORCPT ); Thu, 3 Jun 2004 09:38:36 -0400 To: linux-kernel@vger.kernel.org Path: not-for-mail From: Bill Davidsen Newsgroups: mail.linux-kernel Subject: Re: why swap at all? Date: Thu, 03 Jun 2004 09:38:56 -0400 Organization: TMR Associates, Inc Message-ID: References: <5D3C2276FD64424297729EB733ED1F7606242C53@email1.mitretek.org> <20040527124145.GD22648@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: gatekeeper.tmr.com 1086269684 26413 192.168.12.100 (3 Jun 2004 13:34:44 GMT) X-Complaints-To: abuse@tmr.com User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6b) Gecko/20031208 X-Accept-Language: en-us, en In-Reply-To: <20040527124145.GD22648@holomorphy.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III wrote: > On Thu, May 27, 2004 at 08:31:26AM -0400, Piszcz, Justin Michael wrote: > >>If I have 16GB of ram should I use swap? >>Would swap cause the machine to slow down? > > > Yes. You want swap so you can physically relocate anonymous pages in the > rare case one ends up somewhere it could cause memory pressure against > allocations that can only be satisfied by a restricted range of memory. It would seem that the o/s has enough information to separate pages into categories such as 'part of a program,' 'unwritten user write() data,' 'user read() data sequential," 'user read data random' (read after seek) and the like. It would be nice if admins could do tuning on how the o/s weights giving these memory. The swappiness tuner is certainly a start, in practice it does help with atypical loads. And Nick's latest stuff against 2.6.7-rc1-mm1 certainly seems to work very well on my little 96MB slow box with a few dozen windows open. I would call it the best I've run on this box, ever. -- -bill davidsen (davidsen@tmr.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me