From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Howard Subject: Re: serial flow control appears broken Date: Sat, 04 Aug 2007 11:21:07 -0700 Message-ID: <46B4C393.4020506@howardsilvan.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from gateway.howardsilvan.com ([64.146.212.27]:33040 "EHLO mail.howardsilvan.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756235AbXHDSVM (ORCPT ); Sat, 4 Aug 2007 14:21:12 -0400 In-Reply-To: <2c0942db0707280941n1b9e1f7i9c0de332286e8aac@mail.gmail.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org 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 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.