From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: iproute2-2.6.20-070313 bug ? Date: Thu, 22 Mar 2007 14:09:06 +0100 Message-ID: <46027FF2.6020001@trash.net> References: <20070321175951.M73913@visp.net.lb> <46026717.9060909@trash.net> <20070322124533.M79867@visp.net.lb> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Stephen Hemminger To: Denys Return-path: Received: from stinky.trash.net ([213.144.137.162]:35463 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752326AbXCVNJJ (ORCPT ); Thu, 22 Mar 2007 09:09:09 -0400 In-Reply-To: <20070322124533.M79867@visp.net.lb> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Denys wrote: > /sbin/tc2 qdisc del dev ppp0 root > /sbin/tc2 qdisc add dev ppp0 root handle 1: prio > /sbin/tc2 qdisc add dev ppp0 parent 1:1 handle 2: tbf buffer 1024kb latency > 500ms rate 128kbit peakrate 256kbit minburst 16384 > /sbin/tc2 filter add dev ppp0 parent 1:0 protocol ip prio 10 u32 match ip dst > 0.0.0.0/0 flowid 2:1 That is an incredible huge buffer value. > qdisc tbf 2: parent 1:1 rate 128000bit burst 4294932937b peakrate 256000bit minburst 16Kb lat 4.2s And it causes an overflow. The limit for the TBF burst value with nanosecond resolution is ~ 4 * rate (10^9 * burst / rate < 2^32 needs to hold), resoluting in a worst-case latency of 4 seconds. I think this limit is in the reasonable range. Your configuration results in a worst-case queuing delay of 64s, and I doubt that you really want that. Obviously its not good to break existing configurations, but I would argue that this configuration is broken.