From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266133AbUHPMLj (ORCPT ); Mon, 16 Aug 2004 08:11:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267563AbUHPMLi (ORCPT ); Mon, 16 Aug 2004 08:11:38 -0400 Received: from mailr.eris.qinetiq.com ([128.98.1.9]:37015 "HELO qinetiq-tim.net") by vger.kernel.org with SMTP id S266133AbUHPMLg convert rfc822-to-8bit (ORCPT ); Mon, 16 Aug 2004 08:11:36 -0400 From: Mark Watts Organization: QinetiQ To: Alan Cox Subject: Re: High CPU usage (up to server hang) under heavy I/O load Date: Mon, 16 Aug 2004 13:10:14 +0100 User-Agent: KMail/1.6.1 Cc: Linux Kernel Mailing List References: <20040813140229.4F48B2FC2C@illicom.com> <200408161013.13829.m.watts@eris.qinetiq.com> <1092653845.20528.3.camel@localhost.localdomain> In-Reply-To: <1092653845.20528.3.camel@localhost.localdomain> MIME-Version: 1.0 Content-Disposition: inline Content-Type: Text/Plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Message-Id: <200408161310.14300.m.watts@eris.qinetiq.com> X-AntiVirus: checked by Vexira MailArmor (version: 2.0.1.16; VAE: 6.27.0.4; VDF: 6.27.0.11; host: mailr.qinetiq-tim.net) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > On Llu, 2004-08-16 at 10:13, Mark Watts wrote: > > Would this also mean that if I stick a 64bit SATA raid card (a 3Ware > > 8506-4LP in this case) into a 32bit pci slot, then I/O is always going to > > suck badly? > > > > ... cos I do, and I/O sucks :) > > Seperate issue. > > 64bit DMA is 64bit addressing (ie can DMA from above 4GB). 64bit wide > slot is double the speed for transfers. The 3ware 8xxx I thought could > do 64bit addressing although the driver seems to indicate it cannot, > so with over 4Gb it would hurt. We're running Dual Opterons (Tyan S2875 boards) with 2GB ram. These boards only have 32bit pci slots so we're already not using the full potential of the 3Ware. Basically write performance is a major bottleneck (hardware raid-5 with 250GB sata drives) and writing anything over a few meg usually causes the machine to stall while the write occurs. - -- Mark Watts Senior Systems Engineer QinetiQ Trusted Information Management Trusted Solutions and Services group GPG Public Key ID: 455420ED -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQFBIKQmBn4EFUVUIO0RAjZ3AKDctamutj48XLKCMbY4FSfwgjtXEwCdGHPX bvvd3PNk3SlilysaOYtwa6Y= =rOlr -----END PGP SIGNATURE-----