From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x22f.google.com (mail-lf0-x22f.google.com [IPv6:2a00:1450:4010:c07::22f]) (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 82E763B2A4 for ; Sat, 18 Jun 2016 23:43:16 -0400 (EDT) Received: by mail-lf0-x22f.google.com with SMTP id f6so19268587lfg.0 for ; Sat, 18 Jun 2016 20:43:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=77mM+Q41M7N4muhpabw7fe3njLR9CY+0lWrREuSMDRc=; b=n+NFf/BpBhjNUdsTGAXBEY0jVuJPdq8CWW/Atuw//da8la8D6JEbbh56eefGDeaePi GMZvGBm0Sz5ph9JWI/vtTIpyveFYTCVNILCDnQk7hCAe2kcO0wDqrKW95j/M6B/oTq5d ti0Dz/E5GFMGuEovpMG6ZzgQNsw2IUXBHb9FP2tpq4OPT6/ErF9eR4g+csZBpVpPYSPV Ct14itKXDEbN6WpjBLbUH9CCfm6hfSkjJMHlO8orPOHV/CjMPerTOdPrjfLuYw/L1Z71 4uu/iqRu3dlPr4oZN2IwYnssObhEaoX7mPQrxCWoc7Cu1CD9A0veKbCZNJ7d6GJ/zGtc DaJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=77mM+Q41M7N4muhpabw7fe3njLR9CY+0lWrREuSMDRc=; b=LY7Fp97OfnIZmri6cI6sRpaj1Wm0F1b/mxirBNaQolY7ZtVSqt3mmY8qnF6qxif7gB Fcmu9GdooBDTNNWEwZMhRn7sKiXwThbkUkngL8P3vkJkxF77rWIdr3vFTArrew2nC98t 2J6IPCRXklg+tUHehm/vbJ0NBcU5fVaQTfCW4eN/lTnxZG11HUfAO9XIEEu/9K3tCpN5 oxRl2xOTJDPv+9po4JhOCKPOjqKf38VL4G143s1DPHC35O4iG/xzTWc8e+6OMCZUuN4E PAJ9I3CzUUMNFE2Vgy5Vqcwb28BO2skFDg7myfUdo3/R32im2dzLZwY5nQHf4YE3MIm/ LcHA== X-Gm-Message-State: ALyK8tJ1aEhvJef+UZCzctkR1K3dPXjmLGreVj1U2PgrFEbO9IMOn145oe/oOCBnjx/qOw== X-Received: by 10.25.149.13 with SMTP id x13mr2544989lfd.199.1466307794981; Sat, 18 Jun 2016 20:43:14 -0700 (PDT) Received: from bass.home.chromatix.fi (37-33-112-183.bb.dnainternet.fi. [37.33.112.183]) by smtp.gmail.com with ESMTPSA id a190sm5768451lfe.21.2016.06.18.20.43.11 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 18 Jun 2016 20:43:14 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Jonathan Morton In-Reply-To: Date: Sun, 19 Jun 2016 06:43:01 +0300 Cc: "cerowrt-devel@lists.bufferbloat.net" Content-Transfer-Encoding: quoted-printable Message-Id: <480A221C-E51E-4A77-A0DA-105DD2E0E427@gmail.com> References: To: Dave Taht X-Mailer: Apple Mail (2.3124) Subject: Re: [Cerowrt-devel] qos calculator & paper for htb rate selection X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 19 Jun 2016 03:43:16 -0000 > On 19 Jun, 2016, at 03:53, Dave Taht wrote: >=20 > I was attracted to reading it because > it attempted to take our "85%" rule for sqm-scripts on downloads and > attach some science to it... At no point in that paper did I see any realisation that the initial = burst permitted by a token bucket shaper would typically collect in a = downstream dumb queue. I can forgive them not knowing about = deficit-mode shapers which have no initial burst, but they do not even = try to adjust the burst size of the token bucket shaper. Perhaps they considered that with the link fully loaded during each = test, and with the physical link capacity unrestricted, the size of the = burst was unimportant - but this still meant that a quantity of traffic = at the beginning of each test was transmitted at line rate, not at the = shaped rate. This is an inherent hazard with using a token bucket = shaper as a bandwidth reference. They also seemed to devote a lot of space and effort to determining the = correct queue size for a dump FIFO =E2=80=9Cbehind=E2=80=9D the shaper - = something which AQM would handle for them. When they did add AQM, they = measured the delays to individual bulk flows rather than the delays to = sparse flows competing with the bulk traffic, and thus obtained results = showing AQM giving much larger delays to traffic than an =E2=80=9Coptimall= y sized=E2=80=9D dumb FIFO. As for the optimal sizing, it was performed on a LAN without any delay = lines introduced to simulate realistic Internet RTTs. They therefore = obtained optimal sizes that were very small, and ended up comparing them = against AQMs configured for Internet-scale RTTs, while still in the = low-latency LAN environment. This also gave AQM an unfair handicap. With all these shortcomings, I can=E2=80=99t trust that any of the = results they obtained would have any relevance to a realistic Internet = application. - Jonathan Morton