From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x22e.google.com (mail-lj1-x22e.google.com [IPv6:2a00:1450:4864:20::22e]) (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 892763CB37; Mon, 12 Jul 2021 17:54:04 -0400 (EDT) Received: by mail-lj1-x22e.google.com with SMTP id b40so26613951ljf.12; Mon, 12 Jul 2021 14:54:04 -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=ggEWQNxtzckneaMYJsRlcLmPIT2b8Wj94iHm2kqCeFI=; b=BbTw6mTFoVTXuVX3MCZOo9ksfYxhOXYvlGyv1eU+nSyWErfbedXT31Xq8Mb4Hw6TLb 9lJmCcc8mV2MyeLM0M9PRzMPBMMTmjQrBJo2t1keGAoQNbGO2FrhU5zmLYj8fpO1CmOn o7rIwokOhd0LirbexetWHKIguXpWVbtv9txBK7EsftP2dpodKKJHtvJxeE9lUdCjqnrU zP0GhxiOfmvPlMbPIs2dehKVTpuBoyvbLwZXodc2H2T12fBM7OAkwJfW1RHMaAVWapmi dVtGu/pAZEFmxZ9JiBkWFxbNPJaHKpH6+B4S5d+UvIbsMYMVrEUCiCo8xjbQpopQyACg jbWA== 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=ggEWQNxtzckneaMYJsRlcLmPIT2b8Wj94iHm2kqCeFI=; b=lCzLLeC2O+AHTTDadTc/8UR3xVSug3xGcR1xajIN+QqNeAf9h4hBZeG+V+gD7ejVSD mK4iswYfWQl5tptnwBm+YYQuJtkGd3RAMo1VHV4O3zlyqB7QE2NRcamoqJt5DDlaqXAw mzfmEKwwyrM9YU2osoTLhg7EbrysvGDxRvWkowgtVk2wh/3aRo5pQqwkzVGxC6qHakud iJdDoJKU9+VDgx/JJvQcg4XCElRB3FxS4WWb/MKaQqv0w2LhAn5x+M42I4drUEFyE0rt NbzQZ8DIBb436Hu/RHclm9+0LfhWtwIxVgt8nM1XkCj0jdBZQ5BroqNCIu/gccKE8s6T ux3A== X-Gm-Message-State: AOAM533bhLozBTU3MT6TAN/FW4IhHFWOA8H98vimDZP/qV2YLgLXa0jf ldvNEiZH0j0fmjpgVZV8ppY= X-Google-Smtp-Source: ABdhPJwr50/+7kYnUC+wVrXwfsSuUL8kkMSQEEqZ+oWrcHeRC4D4UgaP4Ruhka/SDWtDE8UepQI86A== X-Received: by 2002:a2e:a7c5:: with SMTP id x5mr1096181ljp.389.1626126843120; Mon, 12 Jul 2021 14:54:03 -0700 (PDT) Received: from jonathartonsmbp.lan (37-136-219-147.rev.dnainternet.fi. [37.136.219.147]) by smtp.gmail.com with ESMTPSA id l25sm1612213ljc.77.2021.07.12.14.54.01 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Jul 2021 14:54:02 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.7\)) From: Jonathan Morton In-Reply-To: Date: Tue, 13 Jul 2021 00:54:00 +0300 Cc: Ben Greear , "starlink@lists.bufferbloat.net" , Make-Wifi-fast , Leonard Kleinrock , "David P. Reed" , Cake List , "Livingood, Jason" , "codel@lists.bufferbloat.net" , cerowrt-devel , bloat Content-Transfer-Encoding: quoted-printable Message-Id: <11FC0C15-A940-4B03-825F-BD62A19E22A2@gmail.com> References: <1625188609.32718319@apps.rackspace.com> <989de0c1-e06c-cda9-ebe6-1f33df8a4c24@candelatech.com> <1625773080.94974089@apps.rackspace.com> <1625859083.09751240@apps.rackspace.com> <1626111630.69692379@apps.rackspace.com> <9c3d61c1-7013-414e-964d-9e83f596e69d@candelatech.com> To: Bob McMahon X-Mailer: Apple Mail (2.3445.9.7) Subject: Re: [Cerowrt-devel] [Make-wifi-fast] [Bloat] Little's Law mea culpa, but not invalidating my main point 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: Mon, 12 Jul 2021 21:54:04 -0000 > On 12 Jul, 2021, at 11:04 pm, Bob McMahon via Make-wifi-fast = wrote: >=20 > "Flow control in store-and-forward computer networks is appropriate = for decentralized execution. A formal description of a class of = "decentralized flow control algorithms" is given. The feasibility of = maximizing power with such algorithms is investigated. On the assumption = that communication links behave like M/M/1 servers it is shown that no = "decentralized flow control algorithm" can maximize network power. Power = has been suggested in the literature as a network performance objective. = It is also shown that no objective based only on the users' throughputs = and average delay is decentralizable. Finally, a restricted class of = algorithms cannot even approximate power." >=20 > https://ieeexplore.ieee.org/document/1095152 >=20 > Did Jaffe make a mistake? I would suggest that if you model traffic as having no control feedback, = you will inevitably find that no control occurs. But real Internet = traffic *does* have control feedback - though it was introduced some = time *after* Jaffe's paper, so we can forgive him for a degree of = ignorance on that point. Perhaps Jaffe effectively predicted the = ARPANET congestion collapse events with his analysis. > Also, it's been observed that latency is non-parametric in it's = distributions and computing gaussians per the central limit theorem for = OWD feedback loops aren't effective. How does one design a control loop = around things that are non-parametric? It also begs the question, what = are the feed forward knobs that can actually help? Control at endpoints benefits greatly from even small amounts of = information supplied by the network about the degree of congestion = present on the path. This is the role played first by packets lost at = queue overflow, then deliberately dropped by AQMs, then marked using the = ECN mechanism rather than dropped. AQM algorithms can be exceedingly simple, or they can be rather = sophisticated. Increased levels of sophistication in both the AQM and = the endpoint's congestion control algorithm may be used to increase the = "network power" actually obtained. The required level of complexity for = each, achieving reasonably good results, is however quite low. - Jonathan Morton=