[tor-relays] Bandwidth Authority PID Feedback Experiment #2 Starting

[Tim Wilde]

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On 12/15/2011 3:43 PM, Mike Perry wrote:
> I've made the following changes this afternoon:
> 
> 1. On the assumption that we're seeing the huge increase in
> variance on torperf because faster nodes are only *sometimes* at
> max capacity, but most of the time have enough spare capacity to
> get good measurements, I have stopped "filtering" measurements for
> them (ie I have stopped selecting only the fast measurements). I am
> still applying filtering to overly punished nodes, so that they
> don't get punished too much by being paired with slow peers.
> 
> 2. I have changed the circ failure target from the network average
> to 0.0% failure.
> 
> 3. I have changed the Guard feedback interval from 2 weeks to 1 
> week.

Mike,

Some more data points for you...

* We relieved the interrupt pressure on our big node by splitting
across two interfaces, and as a result BigBoy has stabilized pretty
well at Bandwidth=1900000 in the consensus, which seems to be right
around the point at which it is consuming CPU in such a way that I
would expect circuit creation errors if it went much higher (so that
seems good).

* However, {Red,Green,Gold,White}Dragon all still seem to be stalled
as far as their actual bandwidth usage, though I do see that their
bandwidth measurements in the consensus have been changing somewhat
(though some have gone down as others have gone up).  I don't see any
indications of failures in their logs (other than the write failures
to the directory authorities periodically).

* Finally, I fired up a new relay on this box yesterday, Ramsgate,
which has not gone above Bandwidth=82 yet.  Pre-experiment (and even
earlier in the experiment) this node would have been able to attract
traffic by now (>12 hours after it was started).

Thanks,
Tim

- -- 
Tim Wilde, Senior Software Engineer, Team Cymru, Inc.
twilde at cymru.com | +1-847-378-3333 | http://www.team-cymru.org/
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