IETF Logo Mail Archive

Re: [tsvwg] L4S status: #17 Interaction w/ FQ AQMs

Pete Heist <pete@heistp.net> Mon, 16 September 2019 08:05 UTC

Return-Path: <pete@heistp.net>
X-Original-To: tsvwg@ietfa.amsl.com
Delivered-To: tsvwg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id DF95412003F for <tsvwg@ietfa.amsl.com>; Mon, 16 Sep 2019 01:05:44 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Level:
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=heistp.net
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 8FLvWRtnPj1u for <tsvwg@ietfa.amsl.com>; Mon, 16 Sep 2019 01:05:43 -0700 (PDT)
Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id E2B281200DE for <tsvwg@ietf.org>; Mon, 16 Sep 2019 01:05:42 -0700 (PDT)
Received: by mail-wm1-x331.google.com with SMTP id r195so9051811wme.2 for <tsvwg@ietf.org>; Mon, 16 Sep 2019 01:05:42 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=heistp.net; s=google; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=06BQ7zpO02OsvH+Jv+vtwv2+Av+AQOsTbx/R2RmSG/M=; b=fSXpfaeBKdgfLxJBKDLqhfYgriGsu2VkxldwA2R7wGWdUtDx8cGhW6x8HYzXXyeMSr Tf2d+Dxgw8n2bwF6uC2S8uvbxpbJwPpB7jEiOunBSUDioIDKL8iP7yNZSY4K27NyDPJh gzzXKhTKCAjv2Wy62B9Hv0/zfQKG7vMWr1quKveYUlqCw2xOo+thhGo3ftLTz96Uyx4Z EL7261gtQZ2wIfwTy22OiIXfAiNHgzkezkWKFuJdPnqRAb+am06SE+3TtS3LhMEMqDfj lYK98/QSwhTF5DK6EYe4boLHLtzyPOVDNNRzwx1Fmzc4NHDTu4EivrUd2oaSicNy169R 4FUg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=06BQ7zpO02OsvH+Jv+vtwv2+Av+AQOsTbx/R2RmSG/M=; b=oBttl4PzsBntNvH3EIjLYkLehVuMYqB8AsSQzQaZ9Gy0+hJht287PdL0u8bUpr9JGI PIm++fTY1/Z9W8CcsyBznAdIa1ks7s/6MSoXKLNlj9Y08tXwGbXp5jR9m6kwRZGmO1gV gpgpLmMD6UKETxesoeI9KfNBR+9EW1X5xdYgWP0pVEamxPR8kSVe00iQmHOH7CGlTSl/ g9v4VCUfUGqXV7OBQtZXKUqPywcjACuf1YrUTYL2sG73dWpb/X2dha99rAAtWrZVmMov s7UBNfglu1Yp1JSHUBlSwBT3vf7jlp3kK4dO+Q6s887lFW08uhVQnUHyhpq9szfZU67x EMBw==
X-Gm-Message-State: APjAAAVBPQvetAEt/6k4WrQaGCyJ6ERfVjFp4gBlvPuHeNp9nRvfIv8w ZReGe4cpbyYoHM2q5Pn/SLXyUA==
X-Google-Smtp-Source: APXvYqzZUXmKv3S8lk/Af0/4jnyS9UW2/JWZRpKUuybVHMsOK5457afCSuS9/wuNPIZpcYfby3BbVw==
X-Received: by 2002:a7b:ce0a:: with SMTP id m10mr8048665wmc.167.1568621141343; Mon, 16 Sep 2019 01:05:41 -0700 (PDT)
Received: from [10.72.0.64] (h-1169.lbcfree.net. [185.193.85.130]) by smtp.gmail.com with ESMTPSA id f66sm11378153wmg.2.2019.09.16.01.05.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 16 Sep 2019 01:05:40 -0700 (PDT)
Content-Type: text/plain; charset="utf-8"
Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\))
From: Pete Heist <pete@heistp.net>
In-Reply-To: <06F55720-52AF-4AD8-9DE1-2ACF8D694239@gmx.de>
Date: Mon, 16 Sep 2019 10:05:39 +0200
Cc: "tsvwg@ietf.org" <tsvwg@ietf.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <1431D1C5-4A52-44A1-A86F-813B72151615@heistp.net>
References: <8321f975-dfe7-694c-b5cc-09fa371b9b61@mti-systems.com> <B58A5572-510E-42C7-8181-42A0BE298393@gmail.com> <D2E12331-F504-4D5F-B8E7-A1A5E98DDF7E@cablelabs.com> <2275E6A5-C8F8-477F-A24A-3E6168917DDF@gmail.com> <55F724CD-6E74-40D9-8416-D1918C2008DD@cablelabs.com> <BBE7C7A9-0222-4D84-BF27-8D5CAE2F995E@gmail.com> <6f189711-ffa0-90f4-fd16-3464ba4df3ce@mti-systems.com> <4A706B11-3239-4DAC-BE85-0B4BFF2D8FF8@heistp.net> <85653C73-449A-4FB0-B15A-F3617B398D29@heistp.net> <06F55720-52AF-4AD8-9DE1-2ACF8D694239@gmx.de>
To: Sebastian Moeller <moeller0@gmx.de>
X-Mailer: Apple Mail (2.3445.9.1)
Archived-At: <https://mailarchive.ietf.org/arch/msg/tsvwg/1HoiAq0TuZFgkqeQJJiAVjCW6cs>
Subject: Re: [tsvwg] L4S status: #17 Interaction w/ FQ AQMs
X-BeenThere: tsvwg@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Transport Area Working Group <tsvwg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tsvwg>, <mailto:tsvwg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tsvwg/>
List-Post: <mailto:tsvwg@ietf.org>
List-Help: <mailto:tsvwg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tsvwg>, <mailto:tsvwg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 16 Sep 2019 08:05:45 -0000

> On Sep 16, 2019, at 9:27 AM, Sebastian Moeller <moeller0@gmx.de> wrote:
> 
> Hi Pete,
> 
> Excellent, thanks.
> 
> So it looks like my fear that L4S-flows would completely crowd out standard compliant flows in the post bottleneck FQ-AQM scenario was unfounded!

If bottleneck 3 were a single queue (‘flows 1’ parameter to fq_codel), that may lead to unfairness, similar to what happens in two-flow competition in Scenario 3:
https://www.heistp.net/downloads/sce-l4s-bakeoff/bakeoff-2019-09-13T045427-r1/l4s-s3-2/batch-l4s-s3-2-cubic-vs-prague-50Mbit-10ms_fixed.png

Note also that in scenario 5-2 for Cubic vs Prague:
https://www.heistp.net/downloads/sce-l4s-bakeoff/bakeoff-2019-09-13T045427-r1/l4s-s5-2/batch-l4s-s5-2-cubic-vs-prague-50Mbit-80ms_fixed.png

the Prague flow exits slow start early, which is at least party influenced by Linux’s default pacing parameters. The early exit from slow start prevents the latency spike on startup of the Prague flow from occurring. On a run of the same test with ss_ratio=100 and ca_ratio=40, which we typically test with for SCE, the early exit from slow start doesn’t happen and results on startup of the Prague flow look different:

https://www.heistp.net/downloads/sce-l4s-bakeoff/bakeoff-2019-09-12T021200-pacing-100/l4s-s5-2/batch-l4s-s5-2-cubic-vs-prague-50Mbit-80ms_fixed.png

v2.23.0 | Report a Bug | By Email