From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out02.uio.no (mail-out02.uio.no [IPv6:2001:700:100:8210::71]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 76FC13BA8E for ; Tue, 27 Nov 2018 16:21:00 -0500 (EST) Received: from mail-mx10.uio.no ([129.240.10.27]) by mail-out02.uio.no with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1gRkmx-0000BI-Fg; Tue, 27 Nov 2018 22:20:59 +0100 Received: from 58.116.34.95.customer.cdi.no ([95.34.116.58] helo=[10.0.0.3]) by mail-mx10.uio.no with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) user michawe (Exim 4.91) (envelope-from ) id 1gRkmw-00048W-WC; Tue, 27 Nov 2018 22:20:59 +0100 From: Michael Welzl Message-Id: Content-Type: multipart/alternative; boundary="Apple-Mail=_B78AE59F-7517-4B46-8108-21ABB601B6D3" Mime-Version: 1.0 (Mac OS X Mail 12.1 \(3445.101.1\)) Date: Tue, 27 Nov 2018 22:20:58 +0100 In-Reply-To: Cc: bloat To: Dave Taht References: <65EAC6C1-4688-46B6-A575-A6C7F2C066C5@heistp.net> <38535869-BF61-4FC4-A0FB-96E91CC4F076@ifi.uio.no> X-Mailer: Apple Mail (2.3445.101.1) X-UiO-SPF-Received: Received-SPF: neutral (mail-mx10.uio.no: 95.34.116.58 is neither permitted nor denied by domain of ifi.uio.no) client-ip=95.34.116.58; envelope-from=michawe@ifi.uio.no; helo=[10.0.0.3]; X-UiO-Spam-info: not spam, SpamAssassin (score=-5.0, required=5.0, autolearn=disabled, HTML_MESSAGE=0.001, TVD_RCVD_IP=0.001, UIO_MAIL_IS_INTERNAL=-5, uiobl=NO, uiouri=NO) X-UiO-Scanned: B20DAAFD31600E162F658F001DDFA1366BAE2E5F Subject: Re: [Bloat] when does the CoDel part of fq_codel help in the real world? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 Nov 2018 21:21:00 -0000 --Apple-Mail=_B78AE59F-7517-4B46-8108-21ABB601B6D3 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Just a small clarification: >> To me the switch to head dropping essentially killed the tail loss = RTO >> problem, eliminated most of the need for ecn. >=20 > I doubt that: TCP will need to retransmit that packet at the head, and = that takes an RTT - all the packets after it will need to wait in the = receiver buffer before the application gets them. > But I don=E2=80=99t have measurements to prove my point, so I=E2=80=99m = just hand-waving=E2=80=A6 I don=E2=80=99t doubt that this kills the tail loss RTO problem. I doubt that it eliminates the need for ECN. Cheers, Michael --Apple-Mail=_B78AE59F-7517-4B46-8108-21ABB601B6D3 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Just = a small clarification:


To me the switch to head = dropping essentially killed the tail loss RTO
problem, eliminated most of the need for = ecn.

I doubt that: TCP will need to retransmit that packet at the = head, and that takes an RTT - all the packets after it will need to wait = in the receiver buffer before the application gets them.
But I don=E2=80=99t have measurements to prove my point, so = I=E2=80=99m just = hand-waving=E2=80=A6

I don=E2=80=99t doubt that this kills the tail loss RTO = problem.
I doubt that it eliminates the need for = ECN.

Cheers,
Michael

= --Apple-Mail=_B78AE59F-7517-4B46-8108-21ABB601B6D3--