3.3.8-6: A reasonably stable CeroWrt version with fq_codel

Posted on Jun 19, 2012 by Dave Täht.

I just put out http://huchra.bufferbloat.net/~cero1/3.3/3.3.8-6/ and deployed it as my default gw and ran a bunch of tests that it survived.

This is a version after 5 development releases and I’m hoping it proves out stable enough for more deploy.

I’d prefer to test 24 hours but I’m about to start a trip and can’t do that. Hopefully after some more testers leap on it we can declare it stable later this week and move on…

Also the source tree is mostly pushed out but a bit of a mess, I don’t know if I’ll be able to get Cero independently buildable before late next week.


  • update to linux 3.3.8
  • Fix for bind9 CVE
  • switch to netifd
  • a complete resync with openwrt - this includes much new stuff,
    including wireless-testing - way too many updates to talk about
    without pulling in the commit log
  • memory problem with ath9k appears gone
  • ECN dropping instituted under load
  • fq_codel packet limits
  • There is now 6rd support, totally untested and unconfigured;
  • transmission bittorrent is in there, too
  • fq_codel on all interfaces by default, on wireless using all 4 subqueues

-s on this release: I went for “stable” rather than new features after it cost me too much time.

  • I had to rip out opkg signing support, and some ipv6/diffserv classification support in transmission that wasn’t fully baked.

  • re-running simple_qos.sh with new values appears to require a reboot first

-The default gui for AQM doesn’t work, the one for “qos” uses hfsc + fq_codel (but lacks ipv6 and diffserv support), and the command line simple_qos.sh has ipv6 and diffserv, but has to be edited and run manually. And perhaps it’s use of htb etc can be improved. I get pretty good results on comcast with simple_qos, see speedtest results here:


but not quite as good as I hoped for. However, under heavier loads the fq_codel stuff is working great under netperf with various numbers of threads and classifications and users.

I would hope some folk here run some benchmarks against various things but some cautions - for example - chrome’s benchmark tends to hit dns
hard, and cero by default is not using your most local forwarder so it can bottleneck on dns - ways to fix that if you have dnssec is to edit
forwarders.conf to point to your local forwarder, and uncomment the forwarders line in named.conf. If your ISP doesn’t
do dnssec yet, disable dnssec and point forwarders.conf to their nameservers - but I otherwise am getting good results.

Also: I would really prefer people clearly identify when they are testing over wireless vs ethernet and until you have a fq_codel and
debloat-script enabled kernel on your laptop, too, I am finding most of the time the bloat is coming from the testing box rather than cerowrt

There are now fq_codel enabled kernels for ubuntu 12.4 and fedora 16 available here:


I look forward to analyzing htb vs hfsc and further tuning of qos-scripts and the simple_qos script. I’m too stupid apparently to
come up with a way to run simple_qos out of the aqm gui… (help wanted)

The new version of quagga-babeld is available in the opkg repository and it has been confirmed to work right with ipv4 mesh interfaces. I
am really looking forward to people trying this and the authentication code now in quagga so we can migrate off of the existing babeld.

Have fun. I am traveling the rest of this week. Patches, benchmarks and data gladly accepted (preferably on the cerowrt-devel list)

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