From: Bob Briscoe <ietf@bobbriscoe.net>
To: Dave Taht <dave.taht@gmail.com>,
ECN-Sane <ecn-sane@lists.bufferbloat.net>
Subject: Re: [Ecn-sane] for the record...
Date: Sat, 26 Feb 2022 14:00:31 +0000 [thread overview]
Message-ID: <141107c3-4e8b-ed3d-88a3-1df26fbe22d7@bobbriscoe.net> (raw)
In-Reply-To: <CAA93jw7pcKBXXvLehkM+Q6TE+r3kymjUbAYiH9HMvU78+jY2ow@mail.gmail.com>
Dave,
I'm replying on the SANE list where this question was posted, but this
is not related to ECN - it's about bugs in the way CoDel recovers its
dropping mode state. Pls move it to a more appropriate list if you want.
See [BB]
On 25/02/2022 21:22, Dave Taht wrote:
> I don't understand the "immediately forgotten" part of this plot. For
> pure non-ect traffic should have hit 50% drop and more or less stayed
> there. With a mix of ect and non ect traffic we should have hit the
> drop_batch facility a lot and never got to a right drop rate.
>
> https://l4steam.github.io/overload-results/
>
[BB] Last Oct I wrote these slides, initially as a notepad for myself,
to work out why 'count' was being forgotten when CoDel re-entered
dropping mode.
https://bobbriscoe.net/projects/latency/CoDel-delta-bug.pdf
I fixed the slides up a bit to try to make them understandable by others.
And I've just added the last slide to put this bug in the context of the
larger design flaw in the control law itself.
I'm not saying my remedies to the bugs are necessarily correct, but at
least the slides explain what the bugs are.
I can't understand how no-one has noticed this bug before tho'.
Bob
--
________________________________________________________________
Bob Briscoe http://bobbriscoe.net/
prev parent reply other threads:[~2022-02-26 14:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-25 21:22 Dave Taht
2022-02-26 14:00 ` Bob Briscoe [this message]
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