[tor-relays] Rampup speed of Exit relay

[teor]

> On 27 Oct. 2016, at 00:32, D. S. Ljungmark <spider at takeit.se> wrote:
> 
> On tis, 2016-10-25 at 22:52 +1100, teor wrote:
>>> 
>>> On 25 Oct. 2016, at 22:26, D.S. Ljungmark <ljungmark at modio.se>
>>> wrote:
>>> 
>>> So, Now I've taken some steps to adjust the state of the relay, and
>>> try to balance this.
>>> 
>>> To reiterate a point previously,  before I start adding more tor
>>> daemons or servers to this, I want to know how to scale and
>>> optimise
>>> what is already there.
>>> 
>>> ...
>>> It's holding between 5k and 16k sockets in use,
>> 
>> Having connections to 6000 relays is normal, and then there are more
>> sockets
>> for Exit traffic.
> 
> Is 6k normal/high/low for an exit?  I'm trying to find the cause of the
> low performance here.

6K - 7K is expected for any relay, as there are that many relays in the
network.

And then an Exit has a socket for every outgoing Internet connection as
well.

>>> and ~3.5k sockets in
>>> TIME_WAIT state.   (Fairly high amount?)
>> 
>> Quite normal for an Exit.
> 
> check.

These are likely from short-lived outgoing Exit connections.

>> Or, the throttling is happening via CPU limiting.
>> 
>> Or, you have an option set that is limiting Tor's bandwidth usage
>> directly.
> 
> Not as far as I'm aware, the only one I've set on purpouse are
> BandwidthBurst / BandwidthRate, both to 92MB.

Clearly you're not hitting these, so you could turn them off.

> On 27 Oct. 2016, at 01:31, D. S. Ljungmark <spider at takeit.se> wrote:
> 
> On ons, 2016-10-26 at 15:32 +0200, D. S. Ljungmark wrote:
>> On tis, 2016-10-25 at 22:52 +1100, teor wrote:
>>> ...
>>> Did you ever try using chutney to measure your local bandwidth?
>>> That will tell you what your CPU is capable of.
>>> (Leaving you to distinguish between config and network.)
>> 
>> No, will do that now to see.
> 
> Chutney in networks/basic-min mode gives me the following on a 500MB
> transfer
> 
> Single Stream Bandwidth: 42.09 MBytes/s
> Overall tor Bandwidth: 168.38 MBytes/s
> 
> Which seems to be in line with where I'd expect things to be CPU wise.
> Not optimum, but at least twice higher than what I see in reality.

You probably want the "Overall tor Bandwidth", which is the bandwidth
of the stream multiplied by the number of tor instances that it goes
through (4: client, guard, middle, exit).

It doesn't account for CPU usage by the python test harness, or the
latency in connection establishment, or any other processes on the
machine. So it will always read lower.

Have you tried monitoring the reliability of connections through your
Exit?

You can run a Tor client with "ExitNodes {fingerprint}", then use Tor
Browser through it. This would help you find out the error messages
clients are getting (if any).

You can also use this to do a bulk transfer test through your exit,
to see if it has any spare bandwidth.

It might also be worth checking what happens to the bandwidth usage
on your Exit over the day and week. A tool like vnstat or munin could
help here.

(Normally, the tor network has daily and weekly peaks.)

T

-- 
Tim Wilson-Brown (teor)

teor2345 at gmail dot com
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