Dummynet AQM v0.1- CoDel and FQ-CoDel for FreeBSD's ipfw/dummynet

[Rasool Al-Saadi]

> -----Original Message-----
> From: Don Lewis [mailto:truckman at FreeBSD.org]
> Sent: Thursday, March 10, 2016 7:29 PM
> To: Rasool Al-Saadi <ralsaadi at swin.edu.au>
> Cc: aqm at ietf.org; freebsd-net at FreeBSD.org; freebsd-ipfw at FreeBSD.org;
> Grenville Armitage <garmitage at swin.edu.au>
> Subject: Re: Dummynet AQM v0.1- CoDel and FQ-CoDel for FreeBSD's
> ipfw/dummynet
> 
> On 26 Feb, Rasool Al-Saadi wrote:
> > Dear all,
> >
> > I would like to announce that we (myself and Grenville Armitage) released
> Dummynet AQM v0.1, which is an independent implementation of CoDel and
> FQ-CoDel for FreeBSD's ipfw/dummynet framework, based on the IETF
> CoDel [1] and FQ-CoDel [2] Internet-Drafts.
> > We prepared patches for FreeBSD11-CURRENT-r295345  and FreeBSD 10.x-
> RELEASE (10.0, 10.1, 10.2), and a technical report  of our implementation.
> >
> > Patches and documentation can be found in:
> > http://caia.swin.edu.au/freebsd/aqm
> >
> > Technical report:
> > http://caia.swin.edu.au/reports/160226A/CAIA-TR-160226A.pdf
> 
> I've got some results with running this on my firewall in an attempt to tame a
> severe bufferbloat problem on my ADSL connection to the outside world.
> 
> The raw speed numbers reported by my ADSL modem are 6016 Kb/s
> downstream and 768 Kb/s upstream.  I set my MTU to 1492 to avoid
> fragmentation from PPPoE overhead.
> 
> Using <http://www.dslreports.com/speedtest> with things unthrottled, I
> observe about 5050 Kb/s downstream and 648Kb/s upstream, with a
> bufferbloat rating of F.
> 
> I configured the system to use FQ-CoDel, with separate pipes for each
> direction.  Because of the slow upstream speed, I increased the target value
> for the upstream direction to 25 ms since a maximum size packet will require
> about 20 ms to send.  I also set the
> net.inet.tcp.experimental.initcwnd10 sysctl value to 0.  The latter seemed to
> help a lot.  With this feature enabled, the initial packet blast at the start of
> the upload caused a large initial latency spike, and the initial transfer rate
> ended up being very slow and it took a long time to ramp up to its maximum
> sustained value.
> 
> My current dummynet pipe bandwidth settings are 4800 Kb/s downstream
> and
> 615 Kb/s upstream.  The speedtest results for these settings are about 4600
> Kb/s downstream and about 600 Kb/s upstream.  I'm somewhat
> disappointed in the bandwith loss, but my bufferbloat rating has improved to
> mostly A's with some B's.
> 
> I do still see a large increase in latency at the start of transfers, and then it
> oscillates for a while before settling down at a reasonable value for the
> remainder of the transfer.  I suspect this is to be expected.
> 
> It would be nice if the implementation was able to account for the PPPOE
> and ATM framing overhead like the Linux implementation does.  I think that
> would help performance when there is a mix of packet sizes.

Dave Täht suggests you to try a "quantum 300" for your 600kbit uplink.

BTW, if you interested try our FQ-PIE implementation in Dummynet AQM v0.2 in your configuration.

Regards,
Rasool