From owner-freebsd-performance@FreeBSD.ORG Thu Oct 1 13:10:45 2009 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0121A1065672 for ; Thu, 1 Oct 2009 13:10:45 +0000 (UTC) (envelope-from wmoran@collaborativefusion.com) Received: from mx00.pub.collaborativefusion.com (mx00.pub.collaborativefusion.com [206.210.89.199]) by mx1.freebsd.org (Postfix) with ESMTP id A8FD08FC0C for ; Thu, 1 Oct 2009 13:10:44 +0000 (UTC) Received: from localhost (overdrive.ws.pitbpa0.priv.collaborativefusion.com [192.168.2.162]) (SSL: TLSv1/SSLv3,256bits,AES256-SHA) by wingspan with esmtp; Thu, 01 Oct 2009 09:10:43 -0400 id 00056419.000000004AC4AA53.000115DD Date: Thu, 1 Oct 2009 09:10:43 -0400 From: Bill Moran To: Dieter Message-Id: <20091001091043.477f4b9b.wmoran@collaborativefusion.com> In-Reply-To: <200909301955.TAA20656@sopwith.solgatos.com> References: <3bbf2fe10909292330t753bcad1r69ae67d7e898ee35@mail.gmail.com> <200909301955.TAA20656@sopwith.solgatos.com> Organization: Collaborative Fusion Inc. X-Mailer: Sylpheed 2.7.1 (GTK+ 2.16.5; i386-portbld-freebsd7.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-performance@freebsd.org Subject: Re: A specific example of a disk i/o problem X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 Oct 2009 13:10:45 -0000 In response to Dieter : > > >> > My question is why is FreeBSD's disk i/o performance so bad? > > > > Here is a specific demo of one disk i/o problem I'm seeing. Should be > > > easy to reproduce? > > > > > > http://lists.freebsd.org/pipermail/freebsd-performance/2008-July/003533.html FYI, I thought I'd play around with this some in an attempt to add some useful information to the investigation. I can not reproduce the problem at all. I created a 9G file, did the cat as described in the above URL, and the man request completed in roughly the same time it did without the cat running. Just to mix it up a bit, I tried running ls -R on a large directory tree while the cat was running as well, and performance did not seem to be significantly impacted there, either. I ran the tests on my work machine, which is a Dell Optiplex 960 running FreeBSD 7.2-RELEASE-p3 i386. Some relevant dmesg stuff: atapci0: port 0xfe80-0xfe87,0xfe90-0xfe93,0xfea0-0xfea7,0xfeb0-0xfeb3,0xfef0-0xfeff irq 18 at device 3.2 on pci0 atapci1: port 0xfe00-0xfe07,0xfe10-0xfe13,0xfe20-0xfe27,0xfe30-0xfe33,0xfec0-0xfedf mem 0xff970000-0xff9707ff irq 18 at device 31.2 on pci0 ad14: 476940MB at ata7-master SATA150 -- Bill Moran Collaborative Fusion Inc. http://people.collaborativefusion.com/~wmoran/