From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) (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 4416B3B29D for ; Sun, 7 Aug 2022 10:10:23 -0400 (EDT) Received: by mail-lf1-x133.google.com with SMTP id c17so9388804lfb.3 for ; Sun, 07 Aug 2022 07:10:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:from:to:cc; bh=6t/lgrCgnM4HXix9xUVcIWPQFQJeaApUXfz0tju3hzQ=; b=m4bMK1Rds1i/hzzAg39k7kqe59IBMKbQ87dziwrpcDVPTDPDu8u9xaPL7L2voOfX9f CDctK7HGRw09MXfK/DwMQvbA6FTQA4TzlOhBfjj4er/YHx0h6Ei3DMeFi0DwMH+mf85C +sNLjuSV8eY/5dG8Ih3+Kr1JMsS6IEtV+fGkNV5pDk+LUmZr+enX1hRs3U2ooLMjCRSm jDttrDqPGo9WUfZqxxuqYSN3v9etqE+LtDBxbINrXP9iQLaHUKl2WImdHK4tR2wI7y7K Jdhe578atHJ6RxUEF6r4ddg4KpfMKlz7kRIhP0TThHKouT7cmX8IlaZdZTr0vh4VGdUB qpGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:x-gm-message-state:from:to:cc; bh=6t/lgrCgnM4HXix9xUVcIWPQFQJeaApUXfz0tju3hzQ=; b=LKrrVpUaKgk1eGtrv9/cmtaauW/kvTSMhTBAeMBLmkVkJBQrxbOeszuwOPQoAqtAdQ MypvwOjUJ0D0Ne+Ydb4cGJ5z/8TaX1gthGVEu4fZzUUDPukMBeu2+GHckN9njIf9zRuQ xm7qiihre0GOqHb3vH31EcgWsWHNV+B9cCiKiCMeAnwLuvjI3JsVKA9GTaP9ZShmBTMU VXQrlWedfaQEhczEJalvPVnD8tWI8Bx/HcGWL5Ytv7zpE6vEZVZ3ScnGdBCfzukMSvXE gI1BRiAxBl2xMdeKMQKCum/CK0ErF4zYaf8rnLClx7fIai+3p8Vpi2zc0MQ2NdO45IZy S8UA== X-Gm-Message-State: ACgBeo2swu1o6Yh8asz8pNWMEFHkJr9X5d+t0LcWv5VYFhoRfjmy0/Lf 5W+gTzNA2DM87vS7FrWv/ak= X-Google-Smtp-Source: AA6agR60QMDjR1u4CKMXiEKd3Wk1nrr8ax8exPjkm33FAzLNUejc6KZVFO5wM62dflLn2b6LZulAMw== X-Received: by 2002:a05:6512:260a:b0:48a:b28f:9630 with SMTP id bt10-20020a056512260a00b0048ab28f9630mr4926496lfb.223.1659881420760; Sun, 07 Aug 2022 07:10:20 -0700 (PDT) Received: from smtpclient.apple (37-136-134-149.rev.dnainternet.fi. [37.136.134.149]) by smtp.gmail.com with ESMTPSA id t18-20020a192d52000000b0048ad13756dcsm1080726lft.223.2022.08.07.07.10.19 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 07 Aug 2022 07:10:20 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.22\)) From: Jonathan Morton In-Reply-To: Date: Sun, 7 Aug 2022 17:10:18 +0300 Cc: Stephen Hemminger , Jonathan Morton via Bloat , =?utf-8?Q?Bj=C3=B8rn_Ivar_Teigen?= Content-Transfer-Encoding: quoted-printable Message-Id: <3E1E9948-7C5B-4A0C-830C-FCB45E191587@gmail.com> References: <20220804162440.57fd5201@hermes.local> To: Daniel Sterling X-Mailer: Apple Mail (2.3654.100.0.2.22) Subject: Re: [Bloat] Researchers discover major roadblock in alleviating network congestion X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 07 Aug 2022 14:10:23 -0000 > On 5 Aug, 2022, at 2:46 am, Daniel Sterling = wrote: >=20 > "Flow control power is non-decentralizable" is from -- 1981? So we've > known for 40 years that TCP streams won't play nicely with each other > unless you shape them at the slower endpoint-- am I understanding that > correctly? But we keep trying anyway? :) More precisely, what was stated in 1981 was: The specific metric of "network power" (the ratio of throughput to = delay, calculated for each flow and globally summed) cannot reliably be = maximised solely by the action of individual endpoints, without = information from within the network itself. Current TCPs generally converge not to maximise or even equalise = "network power", but to equalise between flows a completely different = metric called "RTT fairness", the *product* of throughput and delay. = Adding information from the network via AQMs allows for reductions in = delay with little effect on throughput, and thus a general increase in = network power, but the theoretical global optimum is still not even = approached. Adding FQ in the network, thus implementing "max-min fairness" instead = of "RTT fairness", hence equalising throughput instead of the product of = throughput and delay. This is essentially the geometric mean of = RTT-fairness and network power. I believe it is actually possible to achieve equalisation of network = power between flows, which would approach the global optimum of network = power, using information from the network to guide endpoint behaviour. = This is *only* possible using explicit information from the network, = however, and is not directly compatible with the current = congestion-control paradigm of RTT-fairness by default. - Jonathan Morton=