From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-24-ewr.dyndns.com (mxout-065-ewr.mailhop.org [216.146.33.65]) by lists.bufferbloat.net (Postfix) with ESMTP id 391A22E065B for ; Fri, 4 Feb 2011 09:41:35 -0800 (PST) Received: from scan-22-ewr.mailhop.org (scan-22-ewr.local [10.0.141.244]) by mail-24-ewr.dyndns.com (Postfix) with ESMTP id AFCCD5D0762 for ; Fri, 4 Feb 2011 17:41:33 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 213.186.56.95 Received: from witko.kerneis.info (witko.kerneis.info [213.186.56.95]) by mail-24-ewr.dyndns.com (Postfix) with ESMTP id 0D44D5D05D6 for ; Fri, 4 Feb 2011 17:41:29 +0000 (UTC) Received: from bob75-11-78-249-231-16.fbx.proxad.net ([78.249.231.16] helo=trurl.pps.jussieu.fr) by witko.kerneis.info with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from ) id 1PlPex-0001yT-4j; Fri, 04 Feb 2011 18:41:27 +0100 Received: from jch by trurl.pps.jussieu.fr with local (Exim 4.72) (envelope-from ) id 1PlPeo-0001ME-4D; Fri, 04 Feb 2011 18:41:18 +0100 From: Juliusz Chroboczek To: d@taht.net (Dave =?iso-8859-1?Q?T=E4ht?=) References: <87k4hgdte9.fsf@trurl.pps.jussieu.fr> <87zkqbn896.fsf@cruithne.co.teklibre.org> Date: Fri, 04 Feb 2011 18:41:17 +0100 In-Reply-To: <87zkqbn896.fsf@cruithne.co.teklibre.org> ("Dave =?iso-8859-1?Q?T=E4ht=22's?= message of "Fri, 04 Feb 2011 08:12:53 -0700") Message-ID: <87wrlfd7eq.fsf@trurl.pps.jussieu.fr> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-SA-Exim-Connect-IP: 78.249.231.16 X-SA-Exim-Mail-From: jch@pps.jussieu.fr X-SA-Exim-Scanned: No (on witko.kerneis.info); SAEximRunCond expanded to false Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] About Stochastic Fair Blue (SFB) X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Feb 2011 17:41:35 -0000 > Also, would you mind if I also put the SFB code into git somewhere > on github? It could use a few minor tweaks (make install). If that's okay with you, I'd like to commit it myself. If you suggest the right repo to clone, I'll be glad to do it, and you'll be able to merge it afterwards. > 1) You can hash against multiple combinations of things. For example, in > the home gateway scenario, you could hash against IP addresses only, not > IP/port numbers - to give a per-device level of fairness. Stolen from esfq. > 3) It does packet marking... (So has to be used in combination with > something else) I think you're confused -- it does ECN marking, not netfilter marking. > 1) I don't understand how the penalty box concept works. For each aggregate, sfb maintains a variable, called pdrop, which is the drop probability for this aggregate; the more agressive a flow, the higher pdrop. If the flow is inelastic, i.e. it doesn't slow down in reaction to dropped packets, pdrop reaches 1. At that point, sfb should in principle drop all the packets of this aggregate -- we say that this aggregate has been put in a penalty box. (In my implementation of sfb, I'm not actually dropping all the packets of inelastic flows, I'm just rate-limiting them drastically.) > 2) I don't understand how it would interact with shaping above and > below it There's nothing below sfb, since it's a classless discipline. You may put anything you wish above sfb. If you're the bottleneck and use a driver that performs proper backpressure, it's okay to put nothing; otherwise, you need to put something to simulate backpressure, typically tbf or htb. --Juliusz