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, 21 April 2016 3:12 AM
> To: Rasool Al-Saadi <ralsaadi at swin.edu.au>
> Cc: freebsd-ipfw at FreeBSD.org
> Subject: Re: Dummynet AQM v0.1- CoDel and FQ-CoDel for FreeBSD's
> ipfw/dummynet
> 
> On 20 Apr, Rasool Al-Saadi wrote:
> >
> >
> >> -----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.
> 
> Actually I need to decrease the quantum from 1514 to 1506 in the other
> direction as well.  I decreased the MTU on this path to 1492 to compensate
> for the PPPOE header that is added by my DSL router.  The default 1500 byte
> MTU will result in fragmentation.  If I don't change the quantum to match,
> then periodically two maximal size packets will be allowed from the same
> flow.
> 
> > BTW, if you interested try our FQ-PIE implementation in Dummynet AQM
> v0.2 in your configuration.
> 
> I'm planning on trying that when I have the time.  I also want to test with and
> without ECN on the end station.

If you went to test with ECN, please use Dummynet AQM v0.2 patch as v0.1 has incorrect ECN implementation. 

Regards,
Rasool