From owner-freebsd-net@FreeBSD.ORG Sat Jun 15 03:05:30 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 91ABB518; Sat, 15 Jun 2013 03:05:30 +0000 (UTC) (envelope-from julian@freebsd.org) Received: from vps1.elischer.org (vps1.elischer.org [204.109.63.16]) by mx1.freebsd.org (Postfix) with ESMTP id 66B2315D5; Sat, 15 Jun 2013 03:05:29 +0000 (UTC) Received: from jre-mbp.elischer.org (ppp121-45-237-17.lns20.per1.internode.on.net [121.45.237.17]) (authenticated bits=0) by vps1.elischer.org (8.14.5/8.14.5) with ESMTP id r5F35MA0098643 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Fri, 14 Jun 2013 20:05:26 -0700 (PDT) (envelope-from julian@freebsd.org) Message-ID: <51BBD9EC.3090904@freebsd.org> Date: Sat, 15 Jun 2013 11:05:16 +0800 From: Julian Elischer User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: Luigi Rizzo Subject: Re: [PATH] ALTQ(9) codel algorithm implementation References: <20130614095125.GQ12443@FreeBSD.org> <20130614100828.GA48119@onelab2.iet.unipi.it> In-Reply-To: <20130614100828.GA48119@onelab2.iet.unipi.it> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Ermal Lu?i , freebsd-net X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 15 Jun 2013 03:05:30 -0000 On 6/14/13 6:08 PM, Luigi Rizzo wrote: > On Fri, Jun 14, 2013 at 01:51:25PM +0400, Gleb Smirnoff wrote: >> Ermal, > ... >> I'm afraid we can't grow mbuf packet header with 8 bytes just to satisfy >> the ALTQ codel algo, which would definitely have a limited usage among >> FreeBSD users. Thus, "enqueue_time" should go into mbuf_tags(9) not into >> mbuf packet header. in -current there are currently 2 pad bytes as I just grew it by 16 bits and wanted to get it 32 bit aligned. is there something you can do with 2 bytes to make the overhead less than a tag? tags are not as expensive as they seem however (last I checked). > not to take positions one way or the other, but getting and releasing > a tag on every packet is going to kill performance. > > If i remember well, 2-3 years ago at bsdcan there was discussion > (and mention of some pending work, jeffr maybe ?) > on providing some leading space in the mbuf so one could put there > tags (e.g. ipfw and dummynet ones) without having to allocate them. > Not sure where is this. yes we discussed this and nothing came of it but it's still a valid point of discussion. > > The other thing with codel is that it needs a fairly coarse > timer resolution (100us..1ms) to work so one might be happy > with shorter timestamps (e.g. 4 bytes) if space allows them. > > cheers > luigi > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > >