svn commit: r298131 - head/sys/conf

[Luiz Otavio O Souza]

On Mon, Apr 18, 2016 at 3:19 AM, hiren panchasara wrote:
> On 04/17/16 at 12:20P, Alexander Leidinger wrote:
>>
>> Quoting Luiz Otavio O Souza (from Sat, 16 Apr 2016
>> 20:54:55 +0000 (UTC)):
>>
>> > Author: loos
>> > Date: Sat Apr 16 20:54:55 2016
>> > New Revision: 298131
>> > URL: https://svnweb.freebsd.org/changeset/base/298131
>> >
>> > Log:
>> >   Add Codel to NOTES.
>>
>> I haven't found much documentation about this. It looks like it is
>> only available in PF, but not in dummynet. Is this correct? Are there
>> somewhere examples for the use of codel (options/parameters/HOWTO)? I
>> would expect in places where e.g. "red" could be used, but I don't
>> find any mention of codel in e.g. the FreeBSD handbook.

Yes, this code relies on pf and ALTQ, dummynet support isn't available (yet).

Dummynet support is being worked by Rasool Al-Saadi (see 'Dummynet AQM
v0.2- CoDel, FQ-CoDel, PIE and FQ-PIE for FreeBSD's ipfw/dummynet' in
freebsd-ipfw@)

I agree with the lack of documentation, but I couldn't fix the docs
myself, the ALTQ section hasn't received any update since the pf
import.

Examples bellow.

>
> I'd also appreciate if more details on 1) how to use it 2) under what
> scenarios/workloads would this be most beneficial. And more importantly
> 3) how was this addition validated.

As a parameterless[1] queue algorithm, the usage is very simple:

altq on igb0 codelq queue

This enables codel queueing on output packets for igb0.

Codel can also work together with the other schedulers:

 altq on igb5 hfsc bandwidth 100Mb queue {  q1  }
 queue q1 on igb5 hfsc (  codel, default  )

Codel is expected to help with xDSL links where the link quality can
vary with the time.  Its use should not produce any negative effect.

I'm not aware of any formal validation other than the tests done by
pfSense developers (code was written by eri@ at the time) and the
beneficial results reported by pfSense users over the years.

Luiz


[1]: http://www.bufferbloat.net/projects/codel/wiki