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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next 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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