[tor-relays] Issues reaching gigabit relay speeds

[Matt Traudt]

On 10/30/19 16:30, Mitar wrote:
> Hi!
> 
> I have a gigabit connection and I am trying to utilize it as much as
> possible as a Tor relay. When I try various speed tests I get on the
> machine speeds close to gigabit, but when running Tor, I do not
> achieve anything close to it. I even started two Tor nodes on the same
> machine/connection, see here:
> 
> https://metrics.torproject.org/rs.html#details/567E9785458C605E59202755C74898E3C96FB1CC
> https://metrics.torproject.org/rs.html#details/4CF9BAEB0DE6D7230D6B7DA0FF420C7CFD863885
> 
> The utilization of the machine is pretty low, top returns:
> 
> top - 20:27:33 up 4 days, 23:01,  1 user,  load average: 0.32, 0.28, 0.23
> Tasks: 167 total,   1 running,  97 sleeping,   0 stopped,   0 zombie
> %Cpu(s):  1.6 us,  0.6 sy,  0.0 ni, 97.3 id,  0.0 wa,  0.0 hi,  0.5 si,  0.0 st
> KiB Mem :  3772912 total,   931336 free,  1574676 used,  1266900 buff/cache
> KiB Swap:  3900412 total,  3900412 free,        0 used.  1915568 avail Mem
> 
> In configuration I have:
> 
> RelayBandwidthRate 125 MB
> RelayBandwidthBurst 125 MB
> 
> Interesting is that it seems each Tor daemon on same machine runs
> always around 5 MiB/s, when I started the second one, it just added to
> it with another 5 MiB/s. So it is somewhere else where is the
> bottleneck?
> 
> What could I do to improve things here? To me it looks like more
> throughput should be possible?
> 
> 
> Mitar
> 

You've done everything correctly. Well ... setting RBR and RBB was
probably unnecessary, but it's fine. The problem isn't on your end, if
there's even a problem.

- In an ideal world you won't get more load than your fair share.
Consider a hypothetically large Tor network with loads of high-capacity
relays. Every relay may be capable of 1 Gbps but only see 10 Mbps, yet
there is absolutely no problem.

- That's not to say the current network is anything like this. It's true
exits are the bottleneck right now, but maybe you should expect more
traffic as a non-exit.

- Relays get measured by bandwidth authorities and then load is balanced
across the network based on their measurements. The whole bandwidth
measuring system is a complex mess that produces confusing and
unsatisfying results. Maybe you've gotten unlucky here.

- It's not ideal to be going full tilt all the time. You want to have
some headroom for bursts without causing congestion. Obviously you
aren't even close to that yet.

Thanks for running Tor relays. Sorry I don't have satisfying answers.
Please stick with it and avoid worrying too much about the specific
numbers :)

-- 
Matt