From owner-freebsd-stable@FreeBSD.ORG Sat Aug 14 11:51:00 2010 Return-Path: Delivered-To: stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 35BF41065694; Sat, 14 Aug 2010 11:51:00 +0000 (UTC) (envelope-from pieter@degoeje.nl) Received: from smtp.utwente.nl (smtp1.utsp.utwente.nl [130.89.2.8]) by mx1.freebsd.org (Postfix) with ESMTP id 241B98FC1E; Sat, 14 Aug 2010 11:50:58 +0000 (UTC) Received: from nox-laptop.student.utwente.nl (nox-laptop.student.utwente.nl [130.89.160.140]) by smtp.utwente.nl (8.12.10/SuSE Linux 0.7) with ESMTP id o7EBHLGZ030500; Sat, 14 Aug 2010 13:17:21 +0200 From: Pieter de Goeje To: freebsd-stable@freebsd.org Date: Sat, 14 Aug 2010 13:17:44 +0200 User-Agent: KMail/1.9.10 References: <20100814035751.3436F1CC3B@ptavv.es.net> In-Reply-To: <20100814035751.3436F1CC3B@ptavv.es.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201008141317.45174.pieter@degoeje.nl> X-UTwente-MailScanner-Information: Scanned by MailScanner. Contact icts.servicedesk@utwente.nl for more information. X-UTwente-MailScanner: Found to be clean X-UTwente-MailScanner-From: pieter@degoeje.nl X-Spam-Status: No Cc: stable@freebsd.org, TJ Varghese , Jeremy Chadwick Subject: Re: Inconsistent IO performance X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 14 Aug 2010 11:51:00 -0000 On Saturday 14 August 2010 05:57:51 Kevin Oberman wrote: > > Date: Sat, 14 Aug 2010 11:33:57 +0800 > > From: TJ Varghese > > > > > The deviation in your disk I/O isn't a major surprise (to me anyway), > > > given the system specs. What *does* surprise me is your abysmal I/O > > > speeds in general. 18MB/sec min, 24MB/sec max?! ICH6-M can do a lot > > > more than that. Something isn't right. > > > > it's possible that the hw is...suboptimal. From a 2005 post, > > > > http://forum.thinkpads.com/viewtopic.php?f=2&t=13036&start=0 > > > > Check out the link to the hddbenchmark, > > http://img57.imageshack.us/img57/6430/hddbenchmark1no.jpg > > Thanks, TJ! I guess the disk IO on these boxes simply sucks. Looks like > the 34.75MB/sec sequential read speed is all I can hope for. I'm > guessing the SATA-PATA converter is to blame. Oh, well. > > But all of this does not address my real question, why is performance so > inconsistent? I agree that it sucks, but that does not explain why it > suck so much worse on one run than another. I'm still baffled. > > My backup disk normally odes not leave my office storage cabinet except > when it is in the computer being written, so I don't have it handy > ATM. I will try a couple of things on Monday, though. Perhaps the measurements are taken while the laptop is on a different (less/more stable) surface each time? Disk vibrations could account for the differences. Check out this cool video from Sun: http://news.cnet.com/8301-13556_3-10138666-61.html No idea how this affects sequential read and write workloads however. -- Pieter de Goeje