From owner-freebsd-stable@FreeBSD.ORG Sat Aug 14 08:02:18 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 0D6371065696 for ; Sat, 14 Aug 2010 08:02:18 +0000 (UTC) (envelope-from smithi@nimnet.asn.au) Received: from sola.nimnet.asn.au (paqi.nimnet.asn.au [115.70.110.159]) by mx1.freebsd.org (Postfix) with ESMTP id 1FC4A8FC14 for ; Sat, 14 Aug 2010 08:02:16 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by sola.nimnet.asn.au (8.14.2/8.14.2) with ESMTP id o7E7VKxX051655; Sat, 14 Aug 2010 17:31:20 +1000 (EST) (envelope-from smithi@nimnet.asn.au) Date: Sat, 14 Aug 2010 17:31:20 +1000 (EST) From: Ian Smith To: Kevin Oberman In-Reply-To: <20100814034715.09FE21CC3A@ptavv.es.net> Message-ID: <20100814162034.I77596@sola.nimnet.asn.au> References: <20100814034715.09FE21CC3A@ptavv.es.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Roland Smith , stable@freebsd.org, TJ Varghese 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 08:02:18 -0000 On Fri, 13 Aug 2010, Kevin Oberman wrote: > > Date: Sat, 14 Aug 2010 11:06:58 +0800 > > From: TJ Varghese [..] > > 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. For some sort of comparison, on a T23 (1133MHz P3-M, ICH3 PATA, Fujitsu MHV2120AH 120GB 5400rpm UDMA100 drive, single device on channel, 768MB RAM), I do better than that: # dd if=/dev/ad0 of=/dev/null count=1024 bs=10M gets, over two runs, just either side of 40,500,000 bytes/s. Same result, just slightly better, with bs=512M count=20. (I also tried bs=1024M count=10, but that was really dumb with 768MB RAM :) But with if=/dev/ad0s4 (starts about 70% into the disk) just either side of 29,200,000 bytes/s. All tests show 0.5-0.7% CPU, so hardly a factor, and with that usage powerd kept the CPU at 733MHz. Could be as you suggest, the SATA to PATA converter is a bottleneck? I see mine has acoustic management on also; let us know if it matters? Oh, and that's on 8.0R, about to be brought up to 8.1-S, if relevant. cheers, Ian