From owner-freebsd-stable@FreeBSD.ORG Fri Apr 11 09:57:58 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B18B5106564A for ; Fri, 11 Apr 2008 09:57:58 +0000 (UTC) (envelope-from tom.hurst@clara.net) Received: from spork.qfe3.net (spork.qfe3.net [212.13.207.101]) by mx1.freebsd.org (Postfix) with ESMTP id 76BB48FC1E for ; Fri, 11 Apr 2008 09:57:58 +0000 (UTC) (envelope-from tom.hurst@clara.net) Received: from [81.104.123.28] (helo=voi.aagh.net) by spork.qfe3.net with esmtp (Exim 4.66 (FreeBSD)) (envelope-from ) id 1JkFdE-000EAS-LJ for freebsd-stable@freebsd.org; Fri, 11 Apr 2008 10:33:16 +0100 Received: from freaky by voi.aagh.net with local (Exim 4.69 (FreeBSD)) (envelope-from ) id 1JkFdE-0009BG-Dr for freebsd-stable@freebsd.org; Fri, 11 Apr 2008 10:33:16 +0100 Date: Fri, 11 Apr 2008 10:33:16 +0100 From: Thomas Hurst To: freebsd-stable@freebsd.org Message-ID: <20080411093316.GA31354@voi.aagh.net> Mail-Followup-To: freebsd-stable@freebsd.org References: <20080410223153.GA336@FS.denninger.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080410223153.GA336@FS.denninger.net> Organization: Not much. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: Thomas Hurst Subject: Re: Disk I/O Question 7.0-STABLE 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: Fri, 11 Apr 2008 09:57:58 -0000 * Karl Denninger (karl@denninger.net) wrote: > I have disks on the internal ICH7 adapters (on the motherboard), SATA, > and also a TWE controller with two disks. > > When hitting the TWE controller hard I can hose the I/O performance on > the primary (onboard) adapter quite severely to the point that it > seriously impairs the system's overall performance. "systat -vm" > shows the primary channels going to 100% busy but the transaction and > I/O rate count is not all that high. The twe disk I am hammering, of > course, is saturated (and blowing data at a high rate of speed - > 70MBps+) I see exactly the same behavior on a dual dual core AMD box using amr(4) (8 port LSI MegaRAID SATA) and an 8 port Marvell 88SX6081 ata(4) controller. I have 3 RAID-1 arrays configured on the LSI and a single drive on the Marvell; I can freeze up IO to all of them for several seconds just by running find / >/dev/null for up to 30s. gstat shows the IO queue for one drive in the high hundreds (all writes), and it seems waiting for it to flush is what kills the rest of the system. My best guess is this is a result of the syncer flushing atime updates. I should try mounting my /usr noatime and seeing if the problem goes away. Not the greatest of solutions, but meh. -- Thomas 'Freaky' Hurst http://hur.st/