[metrics-bugs] #29772 [Metrics/Website]: Plot nearly worst-case bandwidth when downloading from [public|onion] server

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#29772: Plot nearly worst-case bandwidth when downloading from [public|onion]
server
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 Reporter:  karsten          |          Owner:  metrics-team
     Type:  enhancement      |         Status:  needs_revision
 Priority:  Medium           |      Milestone:
Component:  Metrics/Website  |        Version:
 Severity:  Normal           |     Resolution:
 Keywords:  scalability      |  Actual Points:
Parent ID:                   |         Points:
 Reviewer:                   |        Sponsor:
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Changes (by irl):

 * status:  needs_review => needs_revision


Comment:

 For the bandwidths, I think that plotting the minimum of the minor
 outliers is OK, we're not excluding many measurements there and we can see
 what the nearly-worst-case is.

 I think for latency, we have to accept that Tor as it currently operates
 is going to have wildly varying latency depending on the path you choose.
 There is currently no way of selecting a "low-latency" path and as we
 increase relay diversity we're going to see these latencies go up. In a
 way, higher latency may indicate greater network diversity.

 For bandwidth, choosing one high bandwidth server compared to another
 isn't going to affect the measurement result. When the network stays the
 same, we are likely to choose a similar set of relays throughout the day
 (or at least, the same consensus weight distribution). For latency, there
 is no consideration so we could be picking relays all over the place, or
 could be picking them all close together.

 The absolute worst cases though, I think we are not hitting that often.
 Plotting the latency per-day may be the wrong approach because we may not
 have enough data points to accurately portray the true latency users
 experience. Perhaps we need a 4-day moving average, at which point some of
 those major outliers are becoming minor outliers and we can plot the
 maximum minor outliers.

 As a data point, when we see a 2000ms latency, that is long enough to get
 a packet through optic fiber to the moon from the earth (not including the
 time to run the fiber, probably with special-purpose rockets). There might
 be some old routing/switching equipment near to relays that is causing
 impact there because this can't just be distance between relays.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29772#comment:6>
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