Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161162AbWASNS0 (ORCPT ); Thu, 19 Jan 2006 08:18:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161176AbWASNSZ (ORCPT ); Thu, 19 Jan 2006 08:18:25 -0500 Received: from out4.smtp.messagingengine.com ([66.111.4.28]:22947 "EHLO out4.smtp.messagingengine.com") by vger.kernel.org with ESMTP id S1161162AbWASNSZ (ORCPT ); Thu, 19 Jan 2006 08:18:25 -0500 X-Sasl-enc: jTcm3/kpQdJexGV/ASj7QvOVIH6P4QGbgPrflpzKSZ1q 1137676703 Message-ID: <43CF919B.1020902@fastmail.co.uk> Date: Thu, 19 Jan 2006 21:18:19 +0800 From: Max Waterman User-Agent: Thunderbird 1.6a1 (Macintosh/20060117) MIME-Version: 1.0 To: Adrian Bunk CC: linux-kernel@vger.kernel.org Subject: Re: io performance... References: <43CB4CC3.4030904@fastmail.co.uk> <20060119004853.GP19398@stusta.de> In-Reply-To: <20060119004853.GP19398@stusta.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2079 Lines: 77 Unfortunately, they don't want me to spend time doing this sort of thing, so I'm out of luck. They're going to stick with 2.6.8-smp, which seems to give the best performance (which rules out your second case below, I suppose). :| Max. Adrian Bunk wrote: > On Mon, Jan 16, 2006 at 03:35:31PM +0800, Max Waterman wrote: >> Hi, >> >> I've been referred to this list from the linux-raid list. >> >> I've been playing with a RAID system, trying to obtain best bandwidth >> from it. >> >> I've noticed that I consistently get better (read) numbers from kernel 2.6.8 >> than from later kernels. >> >> For example, I get 135MB/s on 2.6.8, but I typically get ~90MB/s on later >> kernels. >> >> I'm using this : >> >> >> >> to measure the iorate. I'm using the debian distribution. The h/w is a >> MegaRAID >> 320-2. The array I'm measuring is a RAID0 of 4 Fujitsu Max3073NC 15Krpm >> drives. >> >> The later kernels I've been using are : >> >> 2.6.12-1-686-smp >> 2.6.14-2-686-smp >> 2.6.15-1-686-smp >> >> The kernel which gives us the best results is : >> >> 2.6.8-2-386 >> >> (note that it's not an smp kernel) >> >> I'm testing on an otherwise idle system. >> >> Any ideas to why this might be? Any other advice/help? > > You should try to narrow the problem a bit down. > > Possible causes are: > - kernel regression between 2.6.8 and 2.6.12 > - SMP <-> !SMP support > - patches and/or configuration changes in the Debian kernels > > You should try self-compiled unmodified 2.6.8 and 2.6.12 ftp.kernel.org > kernels with the same .config (modulo differences by "make oldconfig"). > > After this test, you know whether you are in the first case. > If yes, you could do a bisect search for finding the point where the > regression started. > >> Thanks! >> >> Max. > > cu > Adrian > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/