From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265895AbUBCHSh (ORCPT ); Tue, 3 Feb 2004 02:18:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265898AbUBCHSh (ORCPT ); Tue, 3 Feb 2004 02:18:37 -0500 Received: from mail-05.iinet.net.au ([203.59.3.37]:49597 "HELO mail.iinet.net.au") by vger.kernel.org with SMTP id S265895AbUBCHSf (ORCPT ); Tue, 3 Feb 2004 02:18:35 -0500 Message-ID: <401F4A02.7090201@cyberone.com.au> Date: Tue, 03 Feb 2004 18:13:06 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040122 Debian/1.6-1 X-Accept-Language: en MIME-Version: 1.0 To: Samium Gromoff CC: akpm@osdl.org, linux-kernel@vger.kernel.org, philip@codematters.co.uk Subject: Re: 2.6.1 slower than 2.4, smp/scsi/sw-raid/reiserfs References: <87smhsy7n4.wl@canopus.ns.zel.ru> In-Reply-To: <87smhsy7n4.wl@canopus.ns.zel.ru> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Samium Gromoff wrote: >>>The machine is a dual P3 450MHz, 512MB, aic7xxx, 2 disk RAID-0 and >>> ReiserFS. It's a few years old and has always run Linux, most >>> recently 2.4.24. I decided to try 2.6.1 and the performance is >>> disappointing. >>> >> >>2.6 has a few performance problems under heavy pageout at present. Nick >>Piggin has some patches which largely fix it up. >> > >I`m sorry, but this is misguiding. 2.6 does not have a few performance >problems under heavy pageout. > >It`s more like _systematical_ _performance_ _degradation_ increasing with >the pageout rate. The more the box pages out the more 2.6 lags behind 2.4. > > Well it is a few problems that cause significant performance regressions. But nevermind semantics... >What i`m trying to say is that even light paging is affected. And light >paging is warranted when you run, say, KDE on 128M ram. > >Go measure the X desktop startup time on a 48M/64M boxen--even light paging >causes 2.6 to be just sloower. Also the vm thrashing point is much much earlier. > > Have a look here: http://www.kerneltrap.org/~npiggin/vm/3/ and here: http://www.kerneltrap.org/~npiggin/vm/4/ patches here: http://www.kerneltrap.org/~npiggin/vm/ and I have a couple of things which improve results even more. True, its only kbuild, but after I do a bit more tuning I'll focus on other things - I'm hoping most of the improvements carry over to other cases though. Tentatively, it looks like 2.6 under very heavy swapping can actually be significantly improved over 2.4. >Ask Roger Luethi for details. > > Andrew is quite well versed in the details :)