Big bloat update (6 weeks worth!)

Dave Taht d at
Sun Apr 17 22:44:38 EDT 2011

I'd intended to write up summaries of bufferbloat related activity once 
a month, but am running a bit behind. Both JG and I have been travelling 

There's been a lot going on under the covers!

Probably the biggest news is that we are working with Georgia Tech on 
their bismark project. [1] They are out to diagnoise the Internet and we 
are out to fix it. The two goals seemed compatible. In particular: we 
are trying to de-"heisenbug" the test routers so they can accurately 
test the upstream services.

We've also taken the wraps off the "uberwrt" project[2], which is an 
attempt to get the debloating work TESTED in realistic situations at the 
edge and also into openwrt. (Some work from this also flows into bismark)

I was going to write formal joint press releases on these but have been 
too busy traveling, talking and hacking. (if anyone wants to step up to 
handle PR?)

Although traffic on the bloat mailing list has been slow of late, the 
bismark-devel list has been hopping. Feel free to join bismark/uberwrt 
projects and/or the mailing list[3], especially if you are interested in 
embedded hardware.

Moving on to other topics...

Based on the early difficulties in getting debloat-testing to be a 
useful base for the eBDP and A* algorithms, we started looking around 
for ONE driver to work with and have settled on ath9k hardware (for now) 
as a base for routers and wireless cards. [10] We need to do a little 
testing of the laptop cards, but things are looking good.  the 
WNDR3700v2 is AWESOME, actually. 16MB of flash. LUXURY.

Other Patches:

Dan Siemon's pfifo_fast fix for ECN has been backported into 2.6.37.X 
for openwrt's git head as of Saturday. It's also now part of 2.6.39 and 
2.6.38 stable.

SFB is in mainline Linux 2.6.39-RCX and woefully undertested in its 
current incarnation.

Felix Feitkeu has some patches more fully instrumenting the ath9k driver 
(when mildly more complete, these should get slammed into 
debloat-testing as well) [4]

Dan Siemon has improved both his TC shaper test scripts and ping-exp [5]

Media: There were a couple articles on bufferbloat that went by this 
month, I think they were all covered on this list...

There are 236 members of the bloat list now.


We are moving a ton of work to a new build server and also moving the 
lists machine to that. Regrettably as I write, "huchra" is down due to 
finger-foo. It should be back up again Monday.

Multiple other servers in other locations are in the queue. I hope to 
get that sorted out with isc while I am in California.

Upcoming Travel:

JG will be in California April 25-30. I will also be in California April 
25-30 (in at least one of the same places as JG), and am available for 
additional talks/coding/consulting/etc along the western seaboard in 
early May if anyone wants me and can cover my expenses. (Sort of 
scheduled: Byte and Atheros U) I'll also be visiting Seattle at some 
point in May, too.

Travel last month:

JG spent spent several weeks in Europe, first attending the Wireless 
BattleMesh conference[6], then the IETF, giving a shorter version of his 
bufferbloat talk[7].

I spent a week in florida gathering strength for my world tour. Then I 
spent a week with Georgia Tech helping get their Bismark project off the 
ground and hammering out workflow issues.

I was tickled pink when I gave an introductory talk on bufferbloat to a 
class there, only to discover when Q&A rolled around that everyone 
participating was *already* up to speed on bufferbloat and queueing 
disciplines, and peppered me with questions on SFB, RED, eBDP and other 
algorithms we are playing with. 3 months ago I would have been met with 
blank looks, now it's a struggle to keep up!

I then spent a week with esr getting one of the first near-complete 
builds of the wndr3700 working well, working on gpsd (wanted accurate 
time on openwrt) and rsnapshot and split dns and a host of issues... And we also got a revised 
version of the intro to bufferbloat document up on the wiki [8].

I'm very happy to see go ipv6 enabled.

The bufferbloat wiki is still in dire need of love, see the Todo list 
for more details [9] -


And that's all the news I can remember this late Sunday evening. It's my 
hope that SFB will make it into bismark/uberwrt this week so we can test 
SFB a little more while it is still a RC in 2.6.39. I'd VERY MUCH like 
to make sure SFB works when it is released to millions of users 
worldwide. That will be in 4 weeks or so... I'm feeling a little 
schedule pressure here... See dan siemon's scripts... [5]

[1] Georgia Tech's project
[3] (bismark, bismark-devel)
The bandwidth you save may be your own.
[6] has summaries and videos from the battlemesh
[8] The original of the bufferbloat introductory piece was extensively 
discussed on this mailing list. This versions incorporates most of those 
changes. If you don't like this version... It's a wiki document now! 
Please feel free to fix, extend, and add links!
[9] LOTS of writing left

[10] After evaluating multiple routers,

seemed like the best choice

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