From owner-freebsd-stable@FreeBSD.ORG Sat Aug 14 03:47:17 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 1696F1065698 for ; Sat, 14 Aug 2010 03:47:17 +0000 (UTC) (envelope-from oberman@es.net) Received: from mailgw.es.net (mail1.es.net [IPv6:2001:400:201:1::2]) by mx1.freebsd.org (Postfix) with ESMTP id F081A8FC12 for ; Sat, 14 Aug 2010 03:47:16 +0000 (UTC) Received: from ptavv.es.net (ptavv.es.net [IPv6:2001:400:910::29]) by mailgw.es.net (8.14.3/8.14.3) with ESMTP id o7E3lFIQ025058 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Fri, 13 Aug 2010 20:47:15 -0700 Received: from ptavv.es.net (localhost [127.0.0.1]) by ptavv.es.net (Tachyon Server) with ESMTP id 09FE21CC3A; Fri, 13 Aug 2010 20:47:15 -0700 (PDT) To: TJ Varghese In-reply-to: Your message of "Sat, 14 Aug 2010 11:06:58 +0800." Date: Fri, 13 Aug 2010 20:47:15 -0700 From: "Kevin Oberman" Message-Id: <20100814034715.09FE21CC3A@ptavv.es.net> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.0.10011, 1.0.148, 0.0.0000 definitions=2010-08-13_06:2010-08-14, 2010-08-13, 1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx engine=5.0.0-1005130000 definitions=main-1008130244 Cc: Roland Smith , stable@freebsd.org 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 03:47:17 -0000 > Date: Sat, 14 Aug 2010 11:06:58 +0800 > From: TJ Varghese > > > > > > > Maybe there is a hardware component here? Are both disks on the same > > > controller? Or if not are both controllers using the same interrupt line? > > > > No. Each is on its one controller and is the only disk on that > > controller. > > > > > You should have a look at 'systat -vmstat' with dd running in the > > > background. That might give a clue as to where the bottleneck is. > > > > > > > You're using a laptop with 2 HDDs, so does that mean you're using the > Ultrabay for the 2nd HDD? > Perhaps anything connected to that drops down to ATA33 (pure speculation on > my part) since it was designed for optical drives ...dmesg/atacontrol logs > would be useful here. > > You may want to try dd with the of=/dev/null instead to remove the 2nd > variable and benchmark solely the read speed of the 1st hdd. For this test I get a very consistent 34.75 MB. (1000 10M blocks). Distressingly low when there is almost no seek activity. Nope, it is running at UDMA100 using a SATA-PATA converter. (The ICH6 controller is SATA.) But that was a good idea. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751