From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-03-ewr.dyndns.com (mxout-203-ewr.mailhop.org [216.146.33.203]) by lists.bufferbloat.net (Postfix) with ESMTP id 5CF622E044B for ; Fri, 4 Feb 2011 01:46:34 -0800 (PST) Received: from scan-01-ewr.mailhop.org (scanner [10.0.141.223]) by mail-03-ewr.dyndns.com (Postfix) with ESMTP id 05D11788D53 for ; Fri, 4 Feb 2011 09:46:33 +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-03-ewr.dyndns.com (Postfix) with ESMTP id 6ADB5788D91 for ; Fri, 4 Feb 2011 09:46:29 +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 1PlIFI-0008DV-Hs for bloat@lists.bufferbloat.net; Fri, 04 Feb 2011 10:46:28 +0100 Received: from jch by trurl.pps.jussieu.fr with local (Exim 4.72) (envelope-from ) id 1PlIFD-0000dC-1f for bloat@lists.bufferbloat.net; Fri, 04 Feb 2011 10:46:23 +0100 From: Juliusz Chroboczek To: bloat@lists.bufferbloat.net Date: Fri, 04 Feb 2011 10:46:22 +0100 Message-ID: <87k4hgdte9.fsf@trurl.pps.jussieu.fr> 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 Subject: [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 09:46:34 -0000 Hi again, In his series of articles, Jim has concentrated on router-based solutions to delay issues. He mentioned AQM policies in routers, and notably the venerable RED. AQMs are designed to achieve two different (but not necessarily contradictory) goals: to improve the behaviour of the traffic (notably by reducing the amount of buffering, which is what we're concerned about here), and to improve fairness. For example, RED is mostly concerned with the former, while CHOKe is only concerned with the latter. One AQM that attempts both is Stochastic Fair a stochastically-fair variant of BLUE [1]. In addition to reducing buffer size and enforcing rough inter-flow fairness, SFB will reliably detect unresponsive flows and rate-limit them. In order to experiment with SFB, I've implemented it for Linux a couple of years ago [2]. Unfortunately, I've given up for now on trying to get it into the mainline kernel, and I'm not sure I want to try again [3]. --Juliusz [1] W. Feng, D. Kandlur, D. Saha, K. Shin. Blue: A New Class of Active Queue Management Algorithms. U. Michigan CSE-TR-387-99, April 1999. http://www.thefengs.com/wuchang/blue/CSE-TR-387-99.pdf [2] http://www.pps.jussieu.fr/~jch/software/sfb/ [3] http://article.gmane.org/gmane.linux.network/183813