Re: [Codel] [Bloat] better tc support for bittorrent/diffserv

[dave taht <dave.taht@gmail.com>]

On 05/14/2012 11:30 AM, Juliusz Chroboczek wrote:
>> I think, but am not certain, jch is referring to the problem of
>> negotiating ecn over uTP.
> No, I was actually unaware that Linux allows one to set the ECN bits
> from userspace.
It's also possible to get them from userspace.
>
> OTOH, you're right that µTP doesn't currently support ECN.  Not that it
> matters much, ECN is useful for interactive connections (where it can
> avoid a one-RTT delay due to a packet loss) but pretty useless for bulk
> transfers[1].
My scenario is that AQM isn't just for routers anymore.
>
> On a related note, the µTP framing is pretty horrible IMHO, and LEDBAT
> is better implemented within TCP.  Unfortunately, this is not possible
> under Windows (yeah, I got one of the µTorrent guys to contact Microsoft
> on this subject).
>
> On a note related to the related note, Transmission already has the
> ability to make use of a non-default congestion controller for TCP:
>
>    http://www.pps.jussieu.fr/~jch/software/bittorrent/tcp-congestion-control.html

TCP_LEDBAT has been in cerowrt for months. Haven't played with it much, was
mostly comparing westwood and cubic.

http://perso.telecom-paristech.fr/~valenti/pmwiki/pmwiki.php?n=Main.LEDBAT

Also have the ability to exercise alternate algorithms in the latest 
netperf in svn
(as well as classification).

> -- Juliusz
>
> [1] Marek Malowidzki, Simulation-based Study of ECN Performance in RED
>      Networks, In Proc. SPECTS'03. 2003.