From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932349AbWFLV2E (ORCPT ); Mon, 12 Jun 2006 17:28:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932350AbWFLV2E (ORCPT ); Mon, 12 Jun 2006 17:28:04 -0400 Received: from mail.mazunetworks.com ([4.19.249.111]:5032 "EHLO mail.mazunetworks.com") by vger.kernel.org with ESMTP id S932349AbWFLV2B (ORCPT ); Mon, 12 Jun 2006 17:28:01 -0400 Message-ID: <448DDC7F.4030308@mazunetworks.com> Date: Mon, 12 Jun 2006 17:28:31 -0400 From: Jeff Gold User-Agent: Mozilla Thunderbird 1.0.8-1.1.fc4 (X11/20060501) X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: Serial Console and Slow SCSI Disk Access? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Does it make sense that enabling a serial console would reduce the bandwidth of a SCSI disk by more than a factor of ten? This seems crazy to me but there's no arguing with empirical facts. I have an IBM x345 system on which I installed an unmodified 2.6.16.20 kernel built with gcc-4.0.2-8.fc4 (the kernel configuration file I used can be found at http://augart.com/jgold/kconfig). With the control kernel command line I get about 70 MB/sec with hdparm -t but when I add "console=ttyS0,9600 console=tty0" I get about 1.6 MB/sec instead. Here are the complete kernel command lines from grub.conf (the second one doesn't actually include a backslash in grub.conf -- that's just to avoid email wrapping): ro root=/dev/sda3 pci=biosirq loglevel=7 ro root=/dev/sda3 pci=biosirq console=ttyS0,9600n8 console=tty0 \ loglevel=7 I have not been able to connect this behavior to any known kernel bugs using Google or mailing list archives. What might I be doing wrong? Jeff