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

Matt Corallo tor-lists at mattcorallo.com
Fri Jan 10 16:24:56 UTC 2020

Cool! What did your testing rig look like?

I suppose the real question is what does the latency/loss profile of the
average Tor (bridge) user look like?

On 1/10/20 8:18 AM, Roman Mamedov wrote:
> 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.

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