[tor-relays] TCP CCA for Tor Relays (and especially Bridges)

[Roman Mamedov]

On Thu, 9 Jan 2020 00:58:36 -0500
Matt Corallo <tor-lists at mattcorallo.com> wrote:

> BBA should handle random packet loss much better than, eg, Cubic.

Do you mean BBR? https://github.com/google/bbr

In my experience it does work very well on Tor relays, and also on servers in
general (keeping in mind that these TCP congestion control algorithms only
affect upload, so matter most on hosts which do a lot of uploading, or as in
case of Tor both upload and download).

The next best in my tests was Illinois:
https://en.wikipedia.org/wiki/TCP-Illinois I've been using it for a long time
before BBR got included in the Linux kernel. Today, in some cases BBR is
better, in other Illionis can be. The latter ramps up a bit slower on new
connections, but appears to be able to achieve higher speeds after that.

These two are head and shoulders better than all other options available in
the Linux kernel, including the default one (Cubic). And yes, perhaps indeed
this is an area of Tor relay performance tuning that doesn't get enough of the
attention that it deserves.

-- 
With respect,
Roman