From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-x731.google.com (mail-qk1-x731.google.com [IPv6:2607:f8b0:4864:20::731]) (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 381703B2A4; Thu, 20 Oct 2022 10:26:31 -0400 (EDT) Received: by mail-qk1-x731.google.com with SMTP id m6so12857687qkm.4; Thu, 20 Oct 2022 07:26:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:to:references:date:subject:mime-version:from :from:to:cc:subject:date:message-id:reply-to; bh=4o0Sy/IuocxKiJMr2l+W45CQ0xIEZTkVdM5nzWPG56c=; b=cRcBFvNq14umyMdjXeH8KfJWKRRpdIdKSfiAefKYBxd1CLv/peCYJ0ceDdy5f+MXGR u8Ipq8xlcKaRXGDSdYA3JkiWNs2izzSK/eFBnYxeT/hehfS/VNS4MUISo1k7wP7+sdtu IRSN3Ly6LeQUbj5ymtiZcKDInmGOx2ou3x0A2V+aRXvcKX1J5DoXlrSQybAp0lDFwU8g PmF5BO2sQVsUdTsBjemvg/RHoelErrilIilJDTjKt7f2c3M3710tcjdjiSYWtdEMCy/w GoBc3BX2JI3MK3twGjPzMhYyV00h1FUw0Lv0gsrjjiUZ0enrIugSCna5F7zVH4rKCyIe oDgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=message-id:in-reply-to:to:references:date:subject:mime-version:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=4o0Sy/IuocxKiJMr2l+W45CQ0xIEZTkVdM5nzWPG56c=; b=ABVSVMeTyqWiyRcAaFOK+womKKkozECJ1a26R3ioXkhoF53nA0ZUNasf/Eq6nEjGmd dNWc7wNqb5QtRkPtf+0YTROyUpb5ackpugb+7VigfN4UdEKvcZyJt0G2ulsntxfKiC76 PVea2qx8NQ0omVcnzeoKhc2gvLpT8a4p5Ur2q514N3hwqYGMSWGddBGus6ekHwS8kUmA tbSR6M71cPnpf/aOhGrEwwjevo1dqCothdDQeGz8+4+esRhiWlA1F3MuMTBMi6rbJb3m 8oLvWyIBfJICazAsJqvXSIJlGzVgR0GdHXqiTQtUtEfFXLRF19HK9UIbj7ujY5XfimV6 sMQQ== X-Gm-Message-State: ACrzQf3NInyOcI8qJLwiL1dxmMsDca9L0Kss6eX/DHg7eoEsj+IpEBWy rVIqL9o48EYDIR8MRnefPztgb2BxMh0= X-Google-Smtp-Source: AMsMyM6H2bt+QwfnwX9cFmoTZ/koXjdW484uC85LnyjmuSStx6zpHy+jkwuGIceV/GqK3gKuspYBJg== X-Received: by 2002:a05:620a:1b9b:b0:6ed:35f0:9b56 with SMTP id dv27-20020a05620a1b9b00b006ed35f09b56mr9622873qkb.196.1666275990519; Thu, 20 Oct 2022 07:26:30 -0700 (PDT) Received: from [192.168.249.116] ([198.55.239.10]) by smtp.gmail.com with ESMTPSA id g22-20020ac84696000000b0039d03f69cf5sm2660015qto.72.2022.10.20.07.26.29 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Oct 2022 07:26:30 -0700 (PDT) From: Rich Brown Content-Type: multipart/alternative; boundary="Apple-Mail=_BE82F2E3-DBD9-4F11-B2C9-9B5E56EF0599" Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\)) Date: Thu, 20 Oct 2022 10:26:29 -0400 References: <938D9D45-DADA-4291-BD8A-84E4257CEE49@apple.com> <45so9803-49n7-q176-4or6-o188873243s0@ynat.uz> <20221019163614.28437804@hermes.local> To: bloat , Rpm , Make-Wifi-fast In-Reply-To: <20221019163614.28437804@hermes.local> Message-Id: <959408B8-CC1C-4EAD-88DE-C8BF6D112AB9@gmail.com> X-Mailer: Apple Mail (2.3608.120.23.2.7) Subject: Re: [Rpm] [Bloat] [Make-wifi-fast] Traffic analogies (was: Wonderful video) X-BeenThere: rpm@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: revolutions per minute - a new metric for measuring responsiveness List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Oct 2022 14:26:31 -0000 --Apple-Mail=_BE82F2E3-DBD9-4F11-B2C9-9B5E56EF0599 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii > On Oct 19, 2022, at 7:36 PM, Stephen Hemminger via Rpm = wrote: >=20 > Grocery store analogies also breakdown because packets are not = "precious" > it is okay to drop packets. A lot of AQM works by doing "drop early = and often" > instead of "drop late and collapse". Another problem is that grocery store customers are individual flows in = their own right - not correlated with each other. Why is my grocery cart = any more (or less) important than all the others who're waiting? I continue to cast about for intuitive analogies (and getting skunked = each time). But I'm going to try again... Imagine a company with a bunch of employees. (Or a sports venue, or a = UPS depot - any location where a bunch of vehicles with similar = interests all decide to travel at once.) At quitting time, everyone = leaves the parking lot where a traffic cop controls entry onto a = two-lane road.=20 If there isn't any traffic on that road, the traffic cop keeps people = coming out of the driveway "at the maximum rate". If a car approaches on the road, what's the fair strategy for letting = that single car pass? Wait 'til the parking lot empties? Make them wait = 5 minutes? Make them wait one minute? It seems clear to me that it's = fairest to stop traffic right away, let the car pass, then resume the = driveway traffic. This has the advantage of distinguishing between new flows (the single = car) and bulk flows (treating vehicles in the driveway as a single = flow). But it also feels like QoS prioritization or a simple two-queue = model, neither of which lead to the proper intuition.=20 Any "traffic" analogy also ignores people's very real (and correct) = intuition that "cars have mass". They can't stop in an instant and need = to maintain space between them. This also ignores the recently-stated = reality (for routers, at least) that "The best queue is no queue at = all..." Is there any hope of tweaking this analogy? :-) Thanks. Rich= --Apple-Mail=_BE82F2E3-DBD9-4F11-B2C9-9B5E56EF0599 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

On Oct 19, 2022, at 7:36 PM, Stephen Hemminger via Rpm <rpm@lists.bufferbloat.net> wrote:

Grocery store analogies also = breakdown because packets are not "precious"
it is okay to drop packets. A = lot of AQM works by doing "drop early and often"
instead of "drop late and = collapse".

Another problem is that grocery store customers are = individual flows in their own right - not correlated with each other. = Why is my grocery cart any more (or less) important than all the others = who're waiting?

I continue to cast about for intuitive analogies (and getting = skunked each time). But I'm going to try again...
Imagine a company with a bunch of = employees. (Or a sports venue, or a UPS depot - any location where a = bunch of vehicles with similar interests all decide to travel at once.) = At quitting time, everyone leaves the parking lot where a traffic cop = controls entry onto a two-lane road. 

If there isn't any traffic on that = road, the traffic cop keeps people coming out of the driveway "at the = maximum rate".

If a car approaches on the road, what's the fair strategy for = letting that single car pass? Wait 'til the parking lot empties? Make = them wait 5 minutes? Make them wait one minute? It seems clear to me = that it's fairest to stop traffic right away, let the car pass, then = resume the driveway traffic.

This has the advantage of = distinguishing between new flows (the single car) and bulk flows = (treating vehicles in the driveway as a single flow). But it also feels = like QoS prioritization or a simple two-queue model, neither of which = lead to the proper intuition. 

Any "traffic" analogy also ignores = people's very real (and correct) intuition that "cars have mass". They = can't stop in an instant and need to maintain space between them. This = also ignores the recently-stated reality (for routers, at least) that = "The best queue is no queue at all..."

Is there any hope of tweaking this = analogy? :-)

Thanks.

Rich
= --Apple-Mail=_BE82F2E3-DBD9-4F11-B2C9-9B5E56EF0599--