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From: Jonathan Morton <chromatix99@gmail.com>
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Date: Fri, 14 Aug 2015 18:59:08 +0300
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To: Polina Goltsman <polina.goltsman@student.kit.edu>
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Subject: Re: [Codel] [aqm] Codel's count variable and re-entering dropping
	state at small time intervals
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> On 14 Aug, 2015, at 18:25, Polina Goltsman =
<polina.goltsman@student.kit.edu> wrote:
>=20
> What is the default value of "threshold" for default interval and =
target?

=46rom sch_cake.c 694-696:

	fqcd->cparams.target =3D max(byte_target_ns, ns_target);
	fqcd->cparams.interval =3D max(MS2TIME(100) + =
fqcd->cparams.target - ns_target, fqcd->cparams.target * 8);
	fqcd->cparams.threshold =3D (fqcd->cparams.target >> 15) * =
(fqcd->cparams.interval >> 15) * 2;

Given default interval is 100ms (100,000,000 ns) and target is 5ms =
(5,000,000 ns), threshold will be about 931,322.  This is compared to =
the scaled product of sojourn time and the time since the target was =
first exceeded, so its units are not time but time-squared.

The calculation is designed to place the trigger when the queue is =
growing as slowly as possible (ie. resting just above the target sojourn =
time) at twice the nominal interval.  This also places the fastest =
possible trigger at about a third of the nominal interval.

 - Jonathan Morton