From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x232.google.com (mail-lj1-x232.google.com [IPv6:2a00:1450:4864:20::232]) (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 5545A3B29D for ; Thu, 25 Jun 2020 16:42:35 -0400 (EDT) Received: by mail-lj1-x232.google.com with SMTP id x18so8049162lji.1 for ; Thu, 25 Jun 2020 13:42:35 -0700 (PDT) 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 :content-transfer-encoding:message-id:references:to; bh=A0Dqw+ZlZ4/gyU3/Sdddu2yiP3hPIDq70Zm8CtC1re8=; b=o6iObhJ18NCYQd8etHNmh4t7S2CDrN2NOrfNkv8D0kEUOQBiDbXpyDf1ctgSCi0X3x yBLZDl23RFqTYvqr+QO7tM1ulb/mb+kF9dhr6AdHz4xwYbg1am8A2GyRlSM1RHrf2EwQ kCoChR5xC5KyuNa1FBHRoTIeoONdVZdZnlgPOoBzHWVfwarpLOx7OD2EcDwnn6GCA3Zl IK5J1GeICYNzr4gW0b8LRkC3WHczmguqYXCpWGU9hKH87Zl9TKPsuv1d+gUCts+p45cQ GWBWIcAZlhcgBm4Hbsch9EI89j4M5e45811LiBE7wBMTeXCYZ6yaUwWeGCNaQAhiLKCh qPAw== 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=A0Dqw+ZlZ4/gyU3/Sdddu2yiP3hPIDq70Zm8CtC1re8=; b=BbYKKGnERVrH/sSjvDZkIcd5Ev/Paq9s78KDgNMD3bENbtsGm3u4EVvda+FBxIJRom zRn3cFuyujvxP1zGUew1d8ft1ltlK+/R3G/9uqTJTvebyVQPYCqju+Nk5f36EK2xj72h lGMsq0IKq4suWBVNwB7rVEfGfIo+bMCKV9VsIwZkPugdcaPT1sMk6iywywPoZPNXwXcy 06tu1IS86fp3xzzw1nbxt+YVlr/TUL7COUs+HIQhYn0ItuUrUqZXbBsMxHxfhWXqtZZa P1fgoQ5Ui2zuT1JjjMfKvys1HoaeLZfLmUY0vKrdSRnpi9qjydgq0U5m5k0dYtG0L/HC b0zA== X-Gm-Message-State: AOAM530+UguK4pA36s3RkRIIlSmUOoldovOxj/+vt7kYWWtbz4dI8gZ1 0UI1f+j+TSUarE9/FneV6xA= X-Google-Smtp-Source: ABdhPJygAMtj9n7WnMualFC8QtAvkGJj2vqvuNjRQCvh+6WntiBrO0hR/WRlPoQvirxTNTalOEe4kQ== X-Received: by 2002:a2e:7219:: with SMTP id n25mr18452303ljc.164.1593117754202; Thu, 25 Jun 2020 13:42:34 -0700 (PDT) Received: from jonathartonsmbp.lan (83-245-237-85-nat-p.elisa-mobile.fi. [83.245.237.85]) by smtp.gmail.com with ESMTPSA id g22sm6198735lfb.43.2020.06.25.13.42.32 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Jun 2020 13:42:33 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.5\)) From: Jonathan Morton In-Reply-To: Date: Thu, 25 Jun 2020 23:42:31 +0300 Cc: Sebastian Moeller , Cake List Content-Transfer-Encoding: quoted-printable Message-Id: <43093AB9-1B67-487D-B9E1-D52B6D5F5821@gmail.com> References: <8ABBBE20-5045-41CF-967A-CD8961400ABE@darbyshire-bryant.me.uk> <1A34E9D8-C6FD-4E09-866F-DB30F73D6ABC@gmx.de> To: Kevin Darbyshire-Bryant X-Mailer: Apple Mail (2.3445.9.5) Subject: Re: [Cake] Why are target & interval increased on the reduced bandwidth tins? 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, 25 Jun 2020 20:42:35 -0000 > On 25 Jun, 2020, at 4:40 pm, Kevin Darbyshire-Bryant = wrote: >=20 > So the scenario I have in my head says that BK traffic could burst at = full bandwidth rate (or higher) filling upstream ISP buffers and thus = inducing delays on all other traffic because "we think it=E2=80=99s a = slow link and have high interval and target values=E2=80=9D delaying our = response to the burst. Whereas if we retain the default interval & = target from the true link capacity calculation we=E2=80=99ll jump on it = in time. You might be forgetting about ack clocking. This gives the sender = information about how quickly data is reaching the receiver, and = normally the sender will generate either one or two packets for each = packet acked. So even without an immediate AQM action, there is still = *some* restraint on the sender's behaviour within approximately one RTT. This is one of the many subtle factors that Codel relies on. - Jonathan Morton