From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 24 Aug 2001 13:14:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 24 Aug 2001 13:14:42 -0400 Received: from home.linux3d.org ([216.86.203.152]:50940 "EHLO harlot.rb.ca.us") by vger.kernel.org with ESMTP id ; Fri, 24 Aug 2001 13:14:24 -0400 Date: Fri, 24 Aug 2001 10:14:39 -0700 From: Daryll Strauss To: Wilfried Weissmann Cc: Kernel Mailing List Subject: Re: software raid does not do parallel reads under 2.4? Message-ID: <20010824101439.C1717@newbie> In-Reply-To: <20010823234218.B12873@cerebro.laendle> <15238.11161.492557.264988@notabene.cse.unsw.edu.au> <3B868874.B89B04DE@gmx.at> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <3B868874.B89B04DE@gmx.at>; from Wilfried.Weissmann@gmx.at on Fri, Aug 24, 2001 at 07:01:40PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 24, 2001 at 07:01:40PM +0200, Wilfried Weissmann wrote: > I experienced some performance loss when moving from kernel 2.4.4 to > 2.4.7-ac3 regarding ide harddisks. I am useing the hpt ataraid driver > which does pretty much the same thing as the md disk striping driver. > I/O speed of the raid volume is about as fast as accessing a single > drive. > There were a lot of ide reports some time ago. Maybe they where problems > with concurrent I/O operations...? I'm seeing similar behavior with SCSI. I've got two SCSI channels. If I run two dd's each talking to disks on different channels, I get 2x disk bandwidth. If I run two dd's talking to disks on the same channel I get 1x disk bandwidth. This is with 2.4.9, but I haven't isolated which kernel versions cause this. This system has 8 U160 disks spread over 2 U160 channels and it hasn't been deployed yet, so if I can help with testing, let me know. - |Daryll