From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750939AbWFSPOT (ORCPT ); Mon, 19 Jun 2006 11:14:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751025AbWFSPOT (ORCPT ); Mon, 19 Jun 2006 11:14:19 -0400 Received: from mail.mazunetworks.com ([4.19.249.111]:22739 "EHLO mail.mazunetworks.com") by vger.kernel.org with ESMTP id S1750935AbWFSPOT (ORCPT ); Mon, 19 Jun 2006 11:14:19 -0400 Message-ID: <4496BF65.30108@mazunetworks.com> Date: Mon, 19 Jun 2006 11:14:45 -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: Helge Hafting CC: Mark Lord , linux-kernel@vger.kernel.org Subject: Re: Serial Console and Slow SCSI Disk Access? References: <448DDC7F.4030308@mazunetworks.com> <448DDF1D.5020108@rtr.ca> <448DE4F1.9000407@mazunetworks.com> <4496492A.1030907@aitel.hist.no> In-Reply-To: <4496492A.1030907@aitel.hist.no> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Helge Hafting wrote: > With nothing attached, any write to the serial device might go > through a lengthy timeout because of flow control. [...] But I can't > see why it'd make scsi disks slower. The scsi host adapter > initialization writes some messages of course, but there should be no > more console accesses during a hdparm test run. This makes sense to me. When I attach a serial cable and use that to login (I've got agetty running), hdparm produces no console messages that I can see using minicom. Still, the disk throughput is around 1.5 MB/sec for some reason. When I disable the serial console in grub.conf and reboot I get over 70 MB/sec again. A combination of out-of-tree patches (mainly network related but also one to disable PM_TIMERS) seem to eliminate the issue even with the serial console enabled, at least for the moment. That means I no longer have a problem, but the whole thing is mysterious to me. Jeff