[tor-bugs] #29773 [Metrics/Website]: Plot nearly worst-case circuit round-trip latencies to [public|onion] server

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#29773: Plot nearly worst-case circuit round-trip latencies to [public|onion]
server
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     Reporter:  karsten          |      Owner:  metrics-team
         Type:  enhancement      |     Status:  new
     Priority:  Medium           |  Milestone:
    Component:  Metrics/Website  |    Version:
     Severity:  Normal           |   Keywords:
Actual Points:                   |  Parent ID:
       Points:                   |   Reviewer:
      Sponsor:                   |
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 We have been asked to add graphs on (nearly) worst-case performance of our
 OnionPerf measurements, in addition to the average-case performance graphs
 we already have. In particular, we were asked to plot latency and
 bandwidth numbers. This ticket is about latency numbers. It's based on
 team-internal discussions in Brussels and follow-up discussions. This
 ticket is related to #29772.

 We already have graphs on circuit round-trip latencies. They show median
 and interquartile range, as do most of our OnionPerf graphs. Now we're
 asked to add graphs on (nearly) worst-case latencies, so 90th or 95th or
 99th percentile.

 I'm attaching two graphs showing 99th percentile latency. As you can see,
 these graphs are highly susceptible to outliers. I don't really know how
 to fix that. I mean, we could plot 95th percentile and hope there won't be
 outliers in those, but there's no guarantee for that. We could use a log
 scale, but that will make the graph so much harder to interpret. Hmm.

 The coding and deployment effort for bringing this graph on the Tor
 Metrics website would be really small, because we'd simply have to extend
 an existing database view that returns 25th, 50th, and 75th percentile to
 also return 90th, 95th, or 99th percentile.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29773>
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