From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from p-mail1.rd.orange.com (p-mail1.rd.orange.com [195.101.245.15]) by huchra.bufferbloat.net (Postfix) with ESMTP id 34F62208AAD for ; Wed, 25 Sep 2013 08:35:58 -0700 (PDT) Received: from p-mail1.rd.orange.com (localhost.localdomain [127.0.0.1]) by localhost (Postfix) with SMTP id E612D7E4004; Wed, 25 Sep 2013 17:35:55 +0200 (CEST) Received: from ftrdsmtp2.rd.francetelecom.fr (unknown [10.192.128.47]) by p-mail1.rd.orange.com (Postfix) with ESMTP id DC2C47E4003; Wed, 25 Sep 2013 17:35:55 +0200 (CEST) Received: from ftrdmel10.rd.francetelecom.fr ([10.192.128.44]) by ftrdsmtp2.rd.francetelecom.fr with Microsoft SMTPSVC(6.0.3790.4675); Wed, 25 Sep 2013 17:35:55 +0200 Received: from [127.0.0.1] ([10.193.116.12]) by ftrdmel10.rd.francetelecom.fr with Microsoft SMTPSVC(6.0.3790.4675); Wed, 25 Sep 2013 17:35:54 +0200 Message-ID: <5243036F.90302@orange.com> Date: Wed, 25 Sep 2013 17:38:23 +0200 From: Luca MUSCARIELLO User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Eric Dumazet , James Roberts References: <2719938E-E24A-4A06-898F-CE90CBED005C@inria.fr> <1380122152.3165.156.camel@edumazet-glaptop> In-Reply-To: <1380122152.3165.156.camel@edumazet-glaptop> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Antivirus: avast! (VPS 130924-1, 24/09/2013), Outbound message X-Antivirus-Status: Clean X-OriginalArrivalTime: 25 Sep 2013 15:35:55.0002 (UTC) FILETIME=[EC748DA0:01CEBA04] Cc: "aqm@ietf.org" , bloat Subject: Re: [Bloat] [aqm] TSO sizing fixes and the new paced "fq" scheduler in Linux 3.12 X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list Reply-To: MUSCARIELLO Luca IMT/OLN List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Sep 2013 15:35:58 -0000 Le 25/09/2013 17:15, Eric Dumazet a écrit : > On Tue, 2013-09-24 at 14:25 +0200, James Roberts wrote: >> No one responded to Luca's Sept 1 comment (on the bloat list) that the >> new code seems to do tail drop rather than longest queue drop. >> >> >> If this is so, bandwidth sharing will not be fair since FQ alone is >> not enough. This was shown in the previously cited Bell Labs >> paper : http://ect.bell-labs.com/who/stiliadi/papers/jsac99.pdf. The >> following table is copied from the paper. > This paper assumes TCP stack can push cwin packets in the queue. > We no longer have this behavior with linux. > > If you have drops on FQ, then you have a serious problem with your > settings. > > FQ is meant to be used on hosts, not on routers. > > For routers, fq_codel is fine. > > TCP Small Queues limits the number of packets in Qdisc for any tcp flow > (2 packets). Default FQ setting allows 10000 packets. > > You can add tail drop on FQ if you really want, but I never had a single > drop in my FQ settings, on 20Gbps links and thousands of flows. > > Therefore I did not add complexity to solve a non problem. Then, I feel like FQ is a bad name to call this "newFQ". It's an implementation of a fair TCP pacer. Which is very useful, but FQ is kind of misleading, IMHO. Luca > > > > _______________________________________________ > aqm mailing list > aqm@ietf.org > https://www.ietf.org/mailman/listinfo/aqm -- France Telecom R&D - Orange Labs MUSCARIELLO Luca - OLN/NMP/TRM 38 - 40, rue du General Leclerc 92794 Issy Les Moulineaux Cedex 9 - France Tel : +33 (0)1 45 29 60 37 http://perso.rd.francetelecom.fr/muscariello