From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) (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 B5E3D3BA8E for ; Tue, 27 Nov 2018 21:04:06 -0500 (EST) Received: by mail-wr1-x433.google.com with SMTP id l9so24646507wrt.13 for ; Tue, 27 Nov 2018 18:04:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=heistp.net; s=google; h=from:message-id:mime-version:subject:date:in-reply-to:cc:to :references; bh=uHphUOO7WurKXNUVPfSWcqT98oC12YqPeaYgFT4PYTY=; b=Cq6T+MKbkAaW0F0WG3F6q6PdIEFwWbh2e+Z7roJiZBllE7Q8Xv8MvLl/bG4sJ8F8ax WOYrzz1ow7Cv9cjhwZHgrWOj1vGSF0hONplAXFKwGG1xtTlykyPDOVxTC+WPqqsv+aH4 hE/+UB0JLJX0OLh8kfgRzH9Lutq+eZ+gwHCyw/CQHg0ttUJtG6uzRbNWMiEvICVK8j8l Cx1NZodJ96UmKx7dfLQPFSBXKvU2KuPS9na0vLxY0qOUPjmHm58HGGk8wpoxTXSPocg4 hWpmHgRd8TCJlTgQm6RgFHsmhmUgsjwL7OlERLzVIyXlSJI78GBZmyyJy7ZUsXeDLXTu M0IA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:message-id:mime-version:subject:date :in-reply-to:cc:to:references; bh=uHphUOO7WurKXNUVPfSWcqT98oC12YqPeaYgFT4PYTY=; b=A6JcNrvH3ZVPPWJ4S9lQAJOebAYGrAu3XEzHJZMxhmYQ53Y8Wen7TPhr+07mVWYPRB q50FoIJnrAI1NrfQHm7fFA6HcOlDwNHBMNtuXZEzfyjlHC5SEm6hTAIMtCL0RIhJgefO SdLC53UtlWyQhAYpJ3kso9nUZtdLUVqdorYcRSl+41mIuQyHABZjBfXOVNtdq4zdehmT UkosKfKEwrUeO6nmbvBzvMlPA74IVL7TsahYNqsB9UZp9fmQBT32VTnQB/bkbEC+wfJS 1AG3LLcGL8meLslNWQTZip9lf5ApXwQ3oTfS9PsHWOWcXWkpBKo5gabazm30xs8Sb3UA C8sw== X-Gm-Message-State: AA+aEWY3iVJndLUubGCOCwtE1a+igChFnU9XFh1V4KeIpk1yICFYB52e 9SPJA5kOQezNybhGPiktkDkMWQ== X-Google-Smtp-Source: AFSGD/V7ym85/HzbqB6sQ4exWXV9BVVPv+VX5ZIBB/vo9X9Cieq/CCzreUtFdzcpaxkaOffXiop6hA== X-Received: by 2002:adf:f504:: with SMTP id q4mr30902008wro.321.1543370645798; Tue, 27 Nov 2018 18:04:05 -0800 (PST) Received: from tron.luk.heistp.net (h-1169.lbcfree.net. [185.193.85.130]) by smtp.gmail.com with ESMTPSA id m4sm1756577wrw.67.2018.11.27.18.04.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Nov 2018 18:04:05 -0800 (PST) From: Pete Heist Message-Id: Content-Type: multipart/alternative; boundary="Apple-Mail=_41978F0C-1ED0-43A2-B751-3C8210409A82" Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Date: Wed, 28 Nov 2018 03:04:03 +0100 In-Reply-To: Cc: bloat To: Dave Taht References: <65EAC6C1-4688-46B6-A575-A6C7F2C066C5@heistp.net> <38535869-BF61-4FC4-A0FB-96E91CC4F076@ifi.uio.no> X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Bloat] when does the CoDel part of fq_codel help in the real world? 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: Wed, 28 Nov 2018 02:04:07 -0000 --Apple-Mail=_41978F0C-1ED0-43A2-B751-3C8210409A82 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Nov 27, 2018, at 9:10 PM, Dave Taht wrote: >=20 > EVEN with http 2.0/ I would be extremely surprised to learn that many > websites fit it all into one tcp transaction. >=20 > There are very few other examples of TCP traffic requiring a low > latency response. This is the crux of what I was looking for originally- some of these = examples along with what the impact is on TCP itself, and what that = actually means for people. I got that and then some. So for future = readers, here=E2=80=99s an attempt to crudely summarize how CoDel = (specifically as used in fq_codel) helps: For some TCP CC algorithms (probably still most, as of this writing): - reduces TCP RTT at saturation, improving interactivity for single = flows with mixed bulk/interactive traffic like HTTP/2.0 or SSH - smooths data delivery (thus meeting user=E2=80=99s expectations) by = avoiding queue overflow (and tail-drop) in larger queues - increases throughput efficiency with ECN (won=E2=80=99t tackle this = further here!) - reduces memory requirements for TCP buffers Regardless of TCP CC algorithm: - reduces latency for =E2=80=9Cnon-flow=E2=80=9D traffic, such as that = for some encrypted VPNs --Apple-Mail=_41978F0C-1ED0-43A2-B751-3C8210409A82 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
On = Nov 27, 2018, at 9:10 PM, Dave Taht <dave.taht@gmail.com>= wrote:

EVEN with http 2.0/ I would be extremely surprised to learn = that many
websites fit = it all into one tcp transaction.

There are very few other examples of TCP traffic requiring a = low
latency = response.

This = is the crux of what I was looking for originally- some of these examples = along with what the impact is on TCP itself, and what that actually = means for people. I got that and then some. So for future readers, = here=E2=80=99s an attempt to crudely summarize how CoDel (specifically = as used in fq_codel) helps:

For = some TCP CC algorithms (probably still most, as of this = writing):
- reduces TCP RTT at saturation, improving = interactivity for single flows with mixed bulk/interactive traffic like = HTTP/2.0 or SSH
- smooths data delivery (thus meeting user=E2=80= =99s expectations) by avoiding queue overflow (and tail-drop) in larger = queues
- increases throughput efficiency with ECN (won=E2=80=99t= tackle this further here!)
- reduces memory requirements for = TCP buffers

Regardless of = TCP CC algorithm:
- reduces latency for =E2=80=9Cnon-flow=E2=80=9D= traffic, such as that for some encrypted VPNs

= --Apple-Mail=_41978F0C-1ED0-43A2-B751-3C8210409A82--