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From: Sebastian Moeller <moeller0@gmx.de>
In-Reply-To: 
 <CAPwoALwHiF_O3sxbR_L=TqpMkRYXmLZyepYMUnOum48edvD-tg@mail.gmail.com>
Date: Tue, 11 Mar 2025 17:50:18 +0100
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References: 
 <173102880955.241550.13993971509576988201@dt-datatracker-5f77bcf4bd-4q5pd>
 <CAPwoALwHiF_O3sxbR_L=TqpMkRYXmLZyepYMUnOum48edvD-tg@mail.gmail.com>
To: "Mohit P. Tahiliani" <tahiliani=40nitk.edu.in@dmarc.ietf.org>
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Message-ID-Hash: MSN352XXCMCPIMT6JHHCQKEU2E6YLNT4
CC: tsvwg@ietf.org
Precedence: list
Subject: =?utf-8?q?=5Btsvwg=5D_Re=3A_New_Version_Notification_for_draft-tahiliani-tsv?=
 =?utf-8?q?wg-fq-pie-00=2Etxt?=
Archived-At: 
 <https://mailarchive.ietf.org/arch/msg/tsvwg/iFWiVGlhtpHG0LBZ_nHeZ5_pOTQ>

Hi Mohit,


thanks. I like this, short and sweet. I do have a question though =
(probably easy to answer) abgout the following section:

Lastly, if an incoming packet arrives when the total number of enqueued =
packets has already saturated the queue capacity, FQ-PIE drops the =
packet without further processing. In contrast, FQ-CoDel identifies the =
queue with the largest current byte count (i.e., a "fat flow") when the =
queue capacity is saturated and drops half of the packets from this =
queue (up to a maximum of 64 packets, as specified in Section 4.1 of =
[RFC8290]). FQ-PIE does not adopt this approach for the reasons =
explained below.

One thing that fq_codel but als DualQ seem to do on overload is take a =
big shovel instead of a scalpel. So while I have no idea which packets =
to drop, maybe doing a bit more than "close the queue for new comers" =
might be in order. Especially since together with ECN there is the =
potential for an unresponsive flow to fill the queue without feeling the =
"pain" for doing so? Yes, mischievous adversarial traffic might not be a =
target to optimize for, but I wonder how the drop only on enqueue can =
ever be safe with ECN?


> On 26. Jan 2025, at 06:59, Mohit P. Tahiliani =
<tahiliani=3D40nitk.edu.in@dmarc.ietf.org> wrote:
>=20
> Hi all,
>=20
> I submitted an I-D on Flow Queue PIE =
(https://datatracker.ietf.org/doc/draft-tahiliani-tsvwg-fq-pie/) during =
the IETF 121 at Dublin, and mentioned in briefly during the last tsvwg =
session on Friday.
>=20
> Flow Queue PIE is a hybrid packet scheduler and Active Queue =
Management (AQM) algorithm.
>=20
> It has been incorporated into the mainline Linux kernel as a queuing =
discipline (qdisc) and is supported by several Linux distributions. =
Additionally, an implementation of FQ-PIE is available in the ns-3 =
network simulator.
>=20
> If you have feedback or if there is anything missing, please let me =
know.
>=20
> Thanks and Regards,
> Mohit P. Tahiliani
>=20
> ---------- Forwarded message ---------
> From: <internet-drafts@ietf.org>
> Date: Fri, Nov 8, 2024 at 6:50=E2=80=AFAM
> Subject: New Version Notification for =
draft-tahiliani-tsvwg-fq-pie-00.txt
> To: Mohit P. Tahiliani <tahiliani@nitk.edu.in>
>=20
>=20
> A new version of Internet-Draft draft-tahiliani-tsvwg-fq-pie-00.txt =
has been
> successfully submitted by Mohit Tahiliani and posted to the
> IETF repository.
>=20
> Name:     draft-tahiliani-tsvwg-fq-pie
> Revision: 00
> Title:    Flow Queue PIE: A Hybrid Packet Scheduler and Active Queue =
Management Algorithm
> Date:     2024-11-08
> Group:    Individual Submission
> Pages:    8
> URL:      =
https://www.ietf.org/archive/id/draft-tahiliani-tsvwg-fq-pie-00.txt
> Status:   =
https://datatracker.ietf.org/doc/draft-tahiliani-tsvwg-fq-pie/
> HTML:     =
https://www.ietf.org/archive/id/draft-tahiliani-tsvwg-fq-pie-00.html
> HTMLized: =
https://datatracker.ietf.org/doc/html/draft-tahiliani-tsvwg-fq-pie
>=20
>=20
> Abstract:
>=20
>    This document presents Flow Queue Proportional Integral controller
>    Enhanced (FQ-PIE), a hybrid packet scheduler and Active Queue
>    Management (AQM) algorithm to isolate flows and tackle the problem =
of
>    bufferbloat.  FQ-PIE uses hashing to classify incoming packets into
>    different queues and provide flow isolation.  Packets are dequeued =
by
>    using a variant of the round robin scheduler.  Each such flow is
>    managed by the PIE algorithm to maintain high link utilization =
while
>    controlling the queue delay to a target value.
>=20
>=20
>=20
> The IETF Secretariat
>=20
>=20