[tor-relays] Rampup speed of Exit relay

[teor]

> On 22 Sep 2016, at 05:41, nusenu <nusenu at openmailbox.org> wrote:
> 
>>>> So, how do we get tor to move past 100-200Mbit? Is it just a waiting game?
> 
> I'd say just run more instances if you still have resources left and
> want to contribute more bw.
> (obviously also your exit policy influences on how much your instance is
> used)

In my experience, a single Tor instance can use between 100Mbps and 500Mbps.
It's highly dependent on the processor, OpenSSL version, and various network factors.

There are also some random factors in the bandwidth measurement process, including the pair selection for bandwidth measurement. And clients also choose paths randomly. This means some relays get more bandwidth than others by chance.

If you want to use the full capacity of your Exit, run multiple Tor instances.
You can run 2 instances per IPv4 address, using different ports.
Many people choose ORPort 443 and DirPort 80 as their secondary instance ports (this can help clients on networks that only allow those ports), but you can choose any ports you want.

Have you considered configuring an IPv6 ORPort as well?
(It's unlikely to affect traffic, but it will help clients that prefer IPv6.)

>>> How long has the relay been up?
>> 
>> 4 years or so. ( current uptime: 11 hours since reboot, it reboots weekly )
> 
> This relay (5989521A) has been first seen on 2014-04-10 according to
> https://onionoo.torproject.org (still long enough).
> 
> Why do you reboot weekly? Memory leak workaround?

If you reboot weekly, you will take time each week to re-gain consensus weight and various other flags. For example, you will only have the HSDir flag for ~50% of the time. (The Guard flag is also affected, but it's somewhat irrelevant for Exits.)

I'd avoid the reboots if you can, there's a known bug affecting at least the Guard flag and restarts, where a long-lived stable relays are disproportionately impacted compared with new relays. I haven't seen any evidence that it affects other flags or consensus weight, but you could try not restarting and see if that helps.

> ...
> 
>>> Have you tried running 2 Tor instances per IPv4 address?
>> 
>> Previously, currently only one to see what throughput we could get a
>> single Tor exit at.
> 
> OK, so this email is about speed optimizations of a single tor instance
> and not about increasing usage a tor exit server?

Tor is not entirely multi-threaded yet. We still recommend running multiple instances on connections faster than 100 - 300Mbps.
(And the Tor network currently only uses about 40% of capacity anyway, slightly more on Exits - this utilisation level helps keep latency low.)
Later versions have better multithreading and crypto optimisations - thanks for keeping your relay up-to-date.

Tim

Tim Wilson-Brown (teor)

teor2345 at gmail dot com
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xmpp: teor at torproject dot org






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