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, 17 May 2002 07:53:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 17 May 2002 07:53:25 -0400 Received: from krusty.dt.E-Technik.Uni-Dortmund.DE ([129.217.163.1]:59664 "EHLO mail.dt.e-technik.uni-dortmund.de") by vger.kernel.org with ESMTP id ; Fri, 17 May 2002 07:53:25 -0400 Date: Fri, 17 May 2002 13:53:20 +0200 From: Matthias Andree To: Linux-Kernel mailing list Subject: Linux 2.4/2.5 SCSI considerably slower than FreeBSD Message-ID: <20020517115319.GA3204@merlin.emma.line.org> Mail-Followup-To: Linux-Kernel mailing list Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.99i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, Marco Flohrer has posted an inquiry to de.comp.os.unix.linux.hardware [German] that his Seagate 36ES2 was slow with a DawiControl 2976UW (SYM53C875), only around 25 MB/s. I have the same observation with a Fujitsu MAH3182MP with an Adaptec 2940UW Pro which is not much faster. Either bus has an active LVD/SE terminator. Single-user mode, time dd if=/dev/XXX of=/dev/null bs=65536 count=10240 (671,1 MB) linear read. Table shows throughput in decimal MB/s (M = 1,000,000) 2.5 2.4 FBSD max. UWSCSI Fuj MAH3182MP 7200/min 32,1 29,4 35,1 TQ 40 UDMA66 Max 4W060H4 5400/min 27,1 26,7 25,7 66 UDMA66 IBM DTLA307045 7200/min 37,2 37,5 37,2 TQ 2.5 66 UDMA66 WDC AC420400D 5400/min 15,5 15,5 15,5 TQ 2.5 66 -------------- table is in decimal MB/s. 2.4: Linux 2.4.19-pre2-ac3 2.5: Linux 2.5.15 FBSD: FreeBSD 4.6-RC (Tagged Queueing Broken) The IDE drives are attached to a VIA 82C686 (KT133), the Fujitsu (actually an U-160 drive) to the mentioned Adaptec. FBSD gets about 20% better throughput. It's far from perfect, but 90% of the maximum is probably almost as good as we can get. Why is Linux SCSI so slow? -- Matthias Andree