From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out5.uio.no (mail-out5.uio.no [IPv6:2001:700:100:10::17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 6294821F2FC for ; Thu, 21 Aug 2014 03:21:54 -0700 (PDT) Received: from mail-mx6.uio.no ([129.240.10.40]) by mail-out5.uio.no with esmtp (Exim 4.80.1) (envelope-from ) id 1XKPV9-0000LX-77; Thu, 21 Aug 2014 12:21:51 +0200 Received: from boomerang.ifi.uio.no ([129.240.68.135]) by mail-mx6.uio.no with esmtpsa (TLSv1:AES128-SHA:128) user michawe (Exim 4.80.1) (envelope-from ) id 1XKPV8-0005T3-LH; Thu, 21 Aug 2014 12:21:51 +0200 Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: text/plain; charset=us-ascii From: Michael Welzl In-Reply-To: Date: Thu, 21 Aug 2014 12:21:49 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <96292B6B-F49D-4A8A-BD23-DD75399D8DA9@ifi.uio.no> References: <20140804124453.GA19478@ens-lyon.fr> To: Dave Taht X-Mailer: Apple Mail (2.1283) X-UiO-SPF-Received: X-UiO-Ratelimit-Test: rcpts/h 8 msgs/h 3 sum rcpts/h 11 sum msgs/h 5 total rcpts 19355 max rcpts/h 44 ratelimit 0 X-UiO-Spam-info: not spam, SpamAssassin (score=-6.1, required=5.0, autolearn=disabled, RP_MATCHES_RCVD=-1.051, UIO_MAIL_IS_INTERNAL=-5, uiobl=NO, uiouri=NO) X-UiO-Scanned: B9C66861D150F383664910F0BD82B62E4AE09FE1 X-UiO-SPAM-Test: remote_host: 129.240.68.135 spam_score: -60 maxlevel 80 minaction 2 bait 0 mail/h: 3 total 5839 max/h 17 blacklist 0 greylist 0 ratelimit 0 Cc: bloat Subject: Re: [Bloat] Remy: Computer-Generated Congestion Control 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: Thu, 21 Aug 2014 10:21:54 -0000 Dave, About this point that I've seen you make repeatedly: > My biggest problem with all the work so far is that it starts with a > constant baseline 150ms or 100ms RTT, and then try various algorithms > over a wide range of bandwidths, and then elides that base RTT in all > future plots. Unless you read carefully, you don't see that... >=20 > The original bufferbloat experiment was at a physical RTT of 10ms, > with bidirectional traffic flooding the queues in both directions, on > an asymmetric network. I keep waiting for more experimenters to try > that as a baseline experiment. This sounds like a call for reality, when the point is to measure things = that matter to the system you're investigating. E.g., if I'm = investigating TCP, and I don't specifically work on ACK behavior (ACK = congestion control or something like that), I usually don't care much = about the backwards traffic or the asymmetry. Yes it does influence the = measured RTT a bit, but then you argue for using a smaller base RTT = where the impact of this gets smaller too. What matters to the function of congestion controllers is the BDP, and = the buffer size. As for real RTTs, I like pinging wwoz.org because it's = a radio station in New Orleans. I do sometimes listen to it, then I get = traffic via a TCP connection that has this RTT. Very real. My ping delay = is consistently above 110ms. On a side note, I can't help but mention that the "original bufferbloat = experiment" features ping over FQ... measuring ping all by itself, = pretty much :-) Michael