From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x230.google.com (mail-wm0-x230.google.com [IPv6:2a00:1450:400c:c09::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 9CDEF3B29E for ; Thu, 23 Nov 2017 05:25:34 -0500 (EST) Received: by mail-wm0-x230.google.com with SMTP id 128so15445607wmo.3 for ; Thu, 23 Nov 2017 02:25:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc:message-id:references :to; bh=C0Ef9Q65nNjwWMhak0jegNlM2GcZxzCHHS2P5H/Shq8=; b=pJT1Eom065Qi7368BcV4H6DaU0agQyZSC8Sf+vb/mcGBNKCIkGdXLzrUTB1k+wJ0P1 /UXwSGN9xcKIheQbQHNmsy4YFSEUIJ1gRvmW5Kk3wEKJW0Rm6G294XWEQ+EHSGMkIdUu q4LF//btzVS8pdRWs0IZZodXR4IQ7KWlOQ9aLd8wTm/hr2c6/5rvWsm/zOnt5xgggj+9 A0HbmJIiFtuTNv78ef34VZAch9AYUoJNjHxaXf8Cm2fBmsabuWoRq80HCW4SJYPqbjV4 QNRepAJCHnJEctyupc9G89vMgR10HxpAjZUiooaG4hPXitqhQ65AgpAKG86B6+cKA0P3 g3VA== 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 :message-id:references:to; bh=C0Ef9Q65nNjwWMhak0jegNlM2GcZxzCHHS2P5H/Shq8=; b=lZM8Xw1tm0t+1dse+ww34qVKHrMWmaJEAHQdlxtQbos6XmCCQSK/2t29kZDQtSBtB6 5Wfb9ITpqr0gRDjTE/WNPSK3T6vB9aoTkZIHTLqNr0VR0F3cJCzRTYmLbUxgRRy1T93p sGLWBxyqqEusSHTtzpE8pS79XDB7U0F4Up4goPDFsRsWhVTufo5mn8/zlERWn3uKO/yN yjuTefTQswWnmO/Bjbjn/GEJx/wczzRnO7opw8KOXYfXu9+Zn0I8zNybq2Lin2YmU3ct PBkUamkQN/YCuhZ7UKIrS+b0vzqxrfJ9wwb6zJnEKXkAgn/a3xy+U3ub2OG+dmiAZ5dJ EHMg== X-Gm-Message-State: AJaThX6Nk8wNK0c+/KJ2SXYZLLbfBSxl9w1BvPyyyri46CZFnzhHKt2l SLCyhA6B3aGYxhvrVCz6u+Y= X-Google-Smtp-Source: AGs4zMYCY3thKKFEFQxf3Irgg9XveK3XWgMlmt0DgozSPiMI5fpC0dPdhXbGax/3743ciy3/5XJB6w== X-Received: by 10.28.234.71 with SMTP id i68mr6489944wmh.7.1511432733509; Thu, 23 Nov 2017 02:25:33 -0800 (PST) Received: from [10.72.0.130] (h-1169.lbcfree.net. [185.99.119.68]) by smtp.gmail.com with ESMTPSA id n143sm13672554wmd.31.2017.11.23.02.25.32 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 23 Nov 2017 02:25:32 -0800 (PST) Content-Type: multipart/alternative; boundary="Apple-Mail=_606E7BF1-AA25-4451-82F5-9F5BA5EC4CC6" Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Pete Heist In-Reply-To: Date: Thu, 23 Nov 2017 11:25:32 +0100 Cc: Cake List Message-Id: <52C2B216-220C-4C17-882C-9994867E86BB@gmail.com> References: <71FB183D-F848-4513-A6F6-D03FD0F10769@gmail.com> To: Jonathan Morton X-Mailer: Apple Mail (2.3124) Subject: Re: [Cake] lan keyword affects host fairness X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Nov 2017 10:25:34 -0000 --Apple-Mail=_606E7BF1-AA25-4451-82F5-9F5BA5EC4CC6 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Nov 23, 2017, at 10:44 AM, Jonathan Morton = wrote: > This is most likely an interaction of the AQM with Linux' scheduling = latency. >=20 > At the 'lan' setting, the time comstants are similar in magnitude to = the delays induced by Linux itself, so congestion might be signalled = prematurely. The flows will then become sparse and total throughput = reduced, leaving little or no back-pressure for the fairness logic to = work against. >=20 > For this reason, you might have better luck with the next higher RTT = setting. >=20 Thanks=E2=80=A6and using =E2=80=98metro=E2=80=99 (rtt 10ms) does improve = things (two more tests at the end): = https://docs.google.com/spreadsheets/d/1SMXWw2fLfmBRU622urfdvA_Ujsuf_KQ4P3= uyOH1skOM/edit#gid=3D2072687073 In both cases, soft rate limiting to 950mbit when using lower RTTs works = better than relying on bql for the back-pressure (if I=E2=80=99m saying = that right). So it just might be a thing (for the man page?) to avoid confusion. Or a = warning emitted in some cases? Maybe there are other opinions on that... Pete --Apple-Mail=_606E7BF1-AA25-4451-82F5-9F5BA5EC4CC6 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
On Nov 23, 2017, at 10:44 AM, Jonathan Morton <chromatix99@gmail.com> wrote:

This is most likely an interaction of the AQM = with Linux' scheduling latency.

At the = 'lan' setting, the time comstants are similar in magnitude to the delays = induced by Linux itself, so congestion might be signalled = prematurely.  The flows will then become sparse and total = throughput reduced, leaving little or no back-pressure for the fairness = logic to work against.

For this reason, you = might have better luck with the next higher RTT setting.

Thanks=E2=80=A6and using =E2=80=98metro=E2=80=99 = (rtt 10ms) does improve things (two more tests at the end):


In both cases, soft rate limiting to = 950mbit when using lower RTTs works better than relying on bql for the = back-pressure (if I=E2=80=99m saying that right).
So it just might be a thing (for the = man page?) to avoid confusion. Or a warning emitted in some cases? Maybe = there are other opinions on that...

Pete

= --Apple-Mail=_606E7BF1-AA25-4451-82F5-9F5BA5EC4CC6--