From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932391AbWFLVjn (ORCPT ); Mon, 12 Jun 2006 17:39:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932392AbWFLVjn (ORCPT ); Mon, 12 Jun 2006 17:39:43 -0400 Received: from rtr.ca ([64.26.128.89]:41868 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S932391AbWFLVjm (ORCPT ); Mon, 12 Jun 2006 17:39:42 -0400 Message-ID: <448DDF1D.5020108@rtr.ca> Date: Mon, 12 Jun 2006 17:39:41 -0400 From: Mark Lord User-Agent: Thunderbird 1.5.0.4 (X11/20060516) MIME-Version: 1.0 To: Jeff Gold Cc: linux-kernel@vger.kernel.org Subject: Re: Serial Console and Slow SCSI Disk Access? References: <448DDC7F.4030308@mazunetworks.com> In-Reply-To: <448DDC7F.4030308@mazunetworks.com> 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 Jeff Gold wrote: > 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. This can happen if there are kernel messages being printed on the serial console. If all is quiet, I would expect things to be as fast as normal elsewhere. -ml