From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick Mansfield Subject: Re: SCSI Disk layer performance Date: Thu, 29 Jan 2004 07:55:17 -0800 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20040129075516.A1830@beaverton.ibm.com> References: <400FF79A.6050108@wanadoo.es> <4018FC0A.3050309@biotek.uio.no> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from e2.ny.us.ibm.com ([32.97.182.102]:18161 "EHLO e2.ny.us.ibm.com") by vger.kernel.org with ESMTP id S265895AbUA2Pzs (ORCPT ); Thu, 29 Jan 2004 10:55:48 -0500 Content-Disposition: inline In-Reply-To: <4018FC0A.3050309@biotek.uio.no>; from george.magklaras@biotek.uio.no on Thu, Jan 29, 2004 at 01:26:50PM +0100 List-Id: linux-scsi@vger.kernel.org To: George Magklaras Cc: Xose Vazquez Perez , linux-scsi@vger.kernel.org On Thu, Jan 29, 2004 at 01:26:50PM +0100, George Magklaras wrote: > The 2.4.21-9EL might have clever things backported into it, but it is > still missing essential things that can make a difference in the block > layer, like an anticipatory I/O schedule. My impression is that all > 2.4 kernels use the Linus Elevator. That works well with moderate SMP > loads, but it does not perform well on my large-ish Hardware RAID0 > 1.1Tbyte ext3 partition on a Power Vault 220S with a Dell PERC4 host > adapter. The 2.6.1 does work a lot more better in that sense, giving > me an average read of 90 Mbytes/sec as opposed to > 60+somethingMbytes/sec I used to get before with 2.4.21-9ELsmp. > > The new I/O schedulers (let alone driver maturity issues) are the way > to go for maximum performance! I won't place -for the moment- a 2.6 on > a production grade system, but in a couple of releases, I will put 2.4 > in the museum :-) with respect to SCSI I/O performance. How does the anticipatory scheduler compare to the deadline scheduler on your system? What types of IO are you doing? -- Patrick Mansfield