Re: [aqm] CoDel's control law that determines drop frequency

Toke Høiland-Jørgensen <toke@toke.dk> Wed, 30 September 2015 12:25 UTC

Return-Path: <toke@toke.dk>
X-Original-To: aqm@ietfa.amsl.com
Delivered-To: aqm@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BE8C21A6F1E for <aqm@ietfa.amsl.com>; Wed, 30 Sep 2015 05:25:17 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.693
X-Spam-Level:
X-Spam-Status: No, score=-0.693 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HELO_EQ_DK=1.009, MIME_8BIT_HEADER=0.3, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id G4YRV-VJB7PY for <aqm@ietfa.amsl.com>; Wed, 30 Sep 2015 05:25:17 -0700 (PDT)
Received: from mail2.tohojo.dk (mail2.tohojo.dk [77.235.48.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id C758D1A6F15 for <aqm@ietf.org>; Wed, 30 Sep 2015 05:25:16 -0700 (PDT)
X-Virus-Scanned: amavisd-new at mail2.tohojo.dk
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=201310; t=1443615913; bh=Ue6rm16aNogkyajRVsdn2ozPd3eZZzdqaLuHdf8sT9w=; h=From:To:Cc:Subject:References:Date:In-Reply-To; b=cvnzlhJnsTJz5VDPLUWsynMvMgbYq1dr2QnBK6mlBxXLAOg6jKvHS+AB4cvMIo6bd aFwmFtwvsuw6rZojGZDP0RDvaVQD6aibhl128EhAWxbt6U0YIbADc9JLqBtfUBq7sa owQBwe+pSXFuaoJfFDuUAVGMpB90Glf3bkdjBFpU=
Sender: toke@toke.dk
Received: by alrua-kau.kau.toke.dk (Postfix, from userid 1000) id E2324C402C3; Wed, 30 Sep 2015 14:25:12 +0200 (CEST)
From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
To: "Bless\, Roland \(TM\)" <roland.bless@kit.edu>
References: <201311122230.rACMUBmH003536@bagheera.jungle.bt.co.uk> <87wpzfpbd3.fsf@alrua-karlstad.karlstad.toke.dk> <56045CA8.2060103@bobbriscoe.net> <CAPRuP3mmg_-uxmtLUXprCmPyLSUuUA7t2dRZpDs_mwtnTgrSQA@mail.gmail.com> <560BA261.6020206@bobbriscoe.net> <560BA7B9.8020800@student.kit.edu> <877fn8kttv.fsf@toke.dk> <560BD38C.5010806@kit.edu>
Date: Wed, 30 Sep 2015 14:25:12 +0200
In-Reply-To: <560BD38C.5010806@kit.edu> (Roland Bless's message of "Wed, 30 Sep 2015 14:20:28 +0200")
X-Clacks-Overhead: GNU Terry Pratchett
Message-ID: <87lhbojdqv.fsf@toke.dk>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Archived-At: <http://mailarchive.ietf.org/arch/msg/aqm/XY1qIoWIGWh81kVrMVVc2AMPKvs>
Cc: Polina Goltsman <polina.goltsman@student.kit.edu>, Andrew Mcgregor <andrewmcgr@google.com>, Kathleen Nichols <nichols@pollere.com>, Bob Briscoe <ietf@bobbriscoe.net>, Van Jacobson <vanj@google.com>, AQM IETF list <aqm@ietf.org>
Subject: Re: [aqm] CoDel's control law that determines drop frequency
X-BeenThere: aqm@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: "Discussion list for active queue management and flow isolation." <aqm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/aqm>, <mailto:aqm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/aqm/>
List-Post: <mailto:aqm@ietf.org>
List-Help: <mailto:aqm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/aqm>, <mailto:aqm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 30 Sep 2015 12:25:17 -0000

"Bless, Roland (TM)" <roland.bless@kit.edu> writes:

> Am 30.09.2015 um 13:52 schrieb Toke Høiland-Jørgensen:
>> Polina Goltsman <polina.goltsman@student.kit.edu> writes:
>> 
>>>> Early on, Rong Pan showed that it takes CoDel ages to bring high load under
>>>> control. I think this linear increase is the reason.
>>>
>>> Is there a link to this ?
>> 
>> I have an analysis of transient behaviour in my recent paper (section 6.2):
>> http://www.sciencedirect.com/science/article/pii/S1389128615002479
>> 
>> PIE struggles with this too, BTW...
>
> Thanks for the pointer, but I guess that's a different issue.
> If I understood Bob correctly, he was referring to a steady state
> situation with many flows (=high load?) in congestion avoidance phase.
> But maybe Bob can clarify this...

Well, steady state has (by definition) nothing to do with how long it
takes to get there? Once CoDel has found the right scaling point it
stays there, so surely the problem is with transients?

-Toke