From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp26.sms.unimo.it (smtp26.sms.unimo.it [155.185.44.26]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 0EC3421F22F for ; Mon, 27 Apr 2015 05:45:12 -0700 (PDT) Received: from [212.84.39.131] (port=56173 helo=[192.168.15.101]) by smtp26.sms.unimo.it with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1YmiPN-00009Z-Ty; Mon, 27 Apr 2015 14:45:10 +0200 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=windows-1252 From: Paolo Valente In-Reply-To: <87pp6p22ho.fsf@toke.dk> Date: Mon, 27 Apr 2015 14:45:08 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <3E2406CD-0938-4C1F-B171-247CBB5E4C7D@unimore.it> <87zj5u2aho.fsf@toke.dk> <2B5B39C9-A33D-46ED-84C6-56F237284B21@unimore.it> <87pp6p22ho.fsf@toke.dk> To: =?windows-1252?Q?Toke_H=F8iland-J=F8rgensen?= X-Mailer: Apple Mail (2.1878.6) UNIMORE-X-SA-Score: -2.9 Cc: bloat Subject: Re: [Bloat] bufferbloat effects on throughput 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: Mon, 27 Apr 2015 12:45:41 -0000 Il giorno 27/apr/2015, alle ore 14:13, Toke H=F8iland-J=F8rgensen = ha scritto: > Paolo Valente writes: >=20 >> Thanks. So, if I understood correctly, average throughput may or may >> not be affected, but large throughput fluctuations will always occur >> in the presence of bufferbloat. >=20 > I'm always wary of saying 'always', but I'd hazard an 'often' ;) >=20 >> Sorry for my usual refrain, but =85 any pointers to tests, results, >> papers and the like? >=20 > Hmm, not sure if there's any papers dealing specifically with this. > However, it's quite easy to provoke this behaviour. Compare, for > instance, >=20 > http://files.toke.dk/bufferbloat/rrul-pfifo_fast-all_scaled.pdf >=20 > with >=20 > http://files.toke.dk/bufferbloat/rrul-fq_codel-all_scaled.pdf >=20 > The two top graphs on each are throughput (download and upload > respectively). >=20 Thanks. The results shown in your graphs seem unmistakable =85 One question: how can one be sure (if it is possible) that the = fluctuation of the throughput of a TCP flow on a given node is caused by = bufferbloat issues in the node, and not by other factors (such as, e.g., = systematic drops in some other nodes along the path followed by the = flow, with the drops possibly even caused by different reasons than = bufferbloat)? Thanks, Paolo > For the aggregate behaviour, I had some data on that in my = presentation > at the IETF in Hawaii: >=20 > http://www.ietf.org/proceedings/91/slides/slides-91-iccrg-4.pdf >=20 > -Toke -- Paolo Valente =20 Algogroup Dipartimento di Fisica, Informatica e Matematica =09 Via Campi, 213/B 41125 Modena - Italy =20 homepage: http://algogroup.unimore.it/people/paolo/