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From: cloneman <bufferbloat@flamingpc.com>
To: bloat <bloat@lists.bufferbloat.net>
Subject: [Bloat] Tuning fq_codel: are there more best practices for slow connections? (<1mbit)
Date: Thu, 2 Nov 2017 02:01:52 -0400	[thread overview]
Message-ID: <CABQZMoL8McmUhCozpaTeS3qYcxndeA_5Z=g_xu=GdhvxbkFjTA@mail.gmail.com> (raw)

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I'm trying to gather advice for people stuck on older connections. It
appears that having dedictated /micromanged tc classes greatly outperforms
the "no knobs" fq_codel approach for connections with  slow upload speed.

When running a single file upload @350kbps , I've observed the competing
ICMP traffic quickly begin to drop (fq_codel) or be delayed considerably (
under sfq). From reading the tuning best practices page is not optimized
for this scenario. (<2.5mbps)
(
https://www.bufferbloat.net/projects/codel/wiki/Best_practices_for_benchmarking_Codel_and_FQ_Codel/
) fq_codel

Of particular concern is that a no-knobs SFQ works better for me than an
untuned codel ( more delay but much less loss for small flows). People just
flipping the fq_codel button on their router at these low speeds could be
doing themselves a disservice.

I've toyed with increasing the target and this does solve the excessive
drops. I haven't played with limit and quantum all that much.

My go-to solution for this would be different classes, a.k.a. traditional
QoS. But ,  wouldn't it be possible to tune fq_codel punish the large flows
'properly' for this very low bandwidth scenario? Surely <1kb ICMP packets
can squeeze through properly without being dropped if there is 350kbps
available, if the competing flow is managed correctly.

I could create a class filter by packet length, thereby moving ICMP/VoIP to
its own tc class, but  this goes against "no knobs" it seems like I'm
re-inventing the wheel of fair queuing - shouldn't the smallest flows never
be delayed/dropped automatically?

Lowering Quantum below 1500 is confusing, serving a fractional packet in a
time interval?

Is there real value in tuning fq_codel for these connections or should
people migrate to something else like nfq_codel?

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             reply	other threads:[~2017-11-02  6:01 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-02  6:01 cloneman [this message]
2017-11-02  6:42 ` Y
2017-11-02  8:25   ` Sebastian Moeller
2017-11-02 16:33     ` Kathleen Nichols
2017-11-02 16:53       ` Y
2017-11-02 16:58     ` Y
2017-11-02 20:31       ` Sebastian Moeller
2017-11-03  0:31         ` Yutaka
2017-11-03  9:53           ` Sebastian Moeller
2017-11-03 10:10             ` Yutaka
2017-11-03 10:31               ` Sebastian Moeller
2017-11-03 10:51             ` Yutaka
2017-11-02  7:11 ` Jonathan Morton
2017-11-02  8:23 ` Sebastian Moeller

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