From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263285AbTJaMiD (ORCPT ); Fri, 31 Oct 2003 07:38:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263290AbTJaMiD (ORCPT ); Fri, 31 Oct 2003 07:38:03 -0500 Received: from c211-28-147-198.thoms1.vic.optusnet.com.au ([211.28.147.198]:42208 "EHLO mail.kolivas.org") by vger.kernel.org with ESMTP id S263285AbTJaMiB (ORCPT ); Fri, 31 Oct 2003 07:38:01 -0500 From: Con Kolivas To: Roger Luethi , Rik van Riel Subject: Re: 2.6.0-test9 - poor swap performance on low end machines Date: Fri, 31 Oct 2003 23:37:34 +1100 User-Agent: KMail/1.5.3 Cc: Chris Vine , linux-kernel@vger.kernel.org References: <200310292230.12304.chris@cvine.freeserve.co.uk> <20031031112615.GA10530@k3.hellgate.ch> In-Reply-To: <20031031112615.GA10530@k3.hellgate.ch> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200310312337.34778.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 31 Oct 2003 22:26, Roger Luethi wrote: > On Thu, 30 Oct 2003 22:57:23 -0500, Rik van Riel wrote: > > On Wed, 29 Oct 2003, Chris Vine wrote: > > > However, on a low end machine (200MHz Pentium MMX uniprocessor with > > > only 32MB of RAM and 70MB of swap) I get poor performance once > > > extensive use is made of the swap space. > > > > Could you try the patch Con Kolivas posted on the 25th ? > > > > Subject: [PATCH] Autoregulate vm swappiness cleanup > > I suppose it will show some improvement but fail to get performance > anywhere near 2.4 -- at least that's what my own tests found. I've been > working on a break-down of where we're losing it. > Bottom line: It's not simply a price we pay for feature X or Y. It's > all over the map, and thus no single patch can possibly fix it. Yes it will show improvement, and I would like to hear how much given how simple it is, but I agree with you. There is an intrinsic difference in the vm in 2.6 that makes it too hard for multiple running applications to have a small piece of the action instead of giving out big pieces of the action. While it is better in most circumstances I believe you describe well the problem under vm overload. I guess encoding a vm scheduler will help (and clearly 2.8 territory) but at what overhead cost? I have no idea myself, as now I'm pulling catch-phrases out of my arse that I hate hearing others use (see any lkml thread about scheduling from people who don't code). Cheers, Con