Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932857AbXHDSVU (ORCPT ); Sat, 4 Aug 2007 14:21:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759104AbXHDSVN (ORCPT ); Sat, 4 Aug 2007 14:21:13 -0400 Received: from gateway.howardsilvan.com ([64.146.212.27]:33038 "EHLO mail.howardsilvan.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754003AbXHDSVM (ORCPT ); Sat, 4 Aug 2007 14:21:12 -0400 Message-ID: <46B4C393.4020506@howardsilvan.com> Date: Sat, 04 Aug 2007 11:21:07 -0700 From: Lee Howard User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.13) Gecko/20060501 Fedora/1.7.13-1.1.fc4 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ray Lee CC: Paul Fulghum , Tilman Schmidt , Alan Cox , Robert Hancock , linux-serial@vger.kernel.org, tytso@mit.edu, rmk@arm.linux.org.uk, linux-kernel@vger.kernel.org Subject: Re: serial flow control appears broken References: <46A84B4A.6070902@shaw.ca> <46A8C6F1.4080309@howardsilvan.com> <20070726173121.70088a92@the-village.bc.nu> <46A98845.8010806@howardsilvan.com> <46A9F712.70706@imap.cc> <46D33636.7070200@microgate.com> <46AA5A0E.1050600@howardsilvan.com> <1185578908.2989.15.camel@x2> <46AACB4D.7080004@howardsilvan.com> <2c0942db0707280941n1b9e1f7i9c0de332286e8aac@mail.gmail.com> In-Reply-To: <2c0942db0707280941n1b9e1f7i9c0de332286e8aac@mail.gmail.com> 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 Content-Length: 1046 Lines: 30 Ray Lee wrote: >On 7/27/07, Lee Howard wrote: > > >>Curiously, the session at 38400 bps that skipped 858 bytes... coincided, >>not just in sequence but also in precice timing within the session, with >>a small but noticeable disk load that I caused by grepping through a >>hundred session logs. (I can't reproduce it easily, though, because of >>disk caching.) >> >> > >`echo 1 > /proc/sys/vm/drop_caches` will clear out most (all?) of what >the kernel has cached from the drive. It's there just for this kind of >repeatability of tests... > And in repeat tests it is quite evident that IDE disk activity is, indeed, at least part of the problem. As IDE disk activity increases an increased amount of data coming in on the serial port goes missing. Thanks, Lee. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/