From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from masada.superduper.net (masada.superduper.net [85.119.82.91]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 2B6F0201AF7 for ; Wed, 9 May 2012 13:36:10 -0700 (PDT) Received: from snappy-wlan.parc.xerox.com ([13.1.108.21]) by masada.superduper.net with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from ) id 1SSDcE-00006c-GR for codel@lists.bufferbloat.net; Wed, 09 May 2012 21:36:08 +0100 Message-ID: <4FAAD534.2030100@superduper.net> Date: Wed, 09 May 2012 13:36:04 -0700 From: Simon Barber User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: codel@lists.bufferbloat.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -2.9 (--) Subject: [Codel] Worst case conditions - large RTT X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 May 2012 20:36:10 -0000 Codel assesses the minimum delay over a fixed time period (the interval) - what happens when the interval is much smaller that the RTT. For example a tcp stream is experiencing a 2 second RTT (perhaps due to bufferbloat at some point), yet the interval is 100ms. The TCP implementation is a poor one that will ACK a window at a time. Here codel will drop excessively, and cause low throughput? Simon