[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:  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 bandwidth numbers. It's based on
 team-internal discussions in Brussels and follow-up discussions.

 With OnionPerf we measure download times for 50 KiB/1 MiB/5 MiB files that
 we download from our own public web server or onion server. We could use
 our `DATAPERC*` timestamps to extract how long it takes to download a
 specific part of our files and use that to compute average bandwidth.

 We'd like to exclude the transfer start with all the circuit establishment
 and TCP slow start stuff and only focus on the parts when things have
 stabilized. More precisely, we could look at the 5 MiB downloads and
 consider only the time between finishing 2.5 MiB of it as well as the full
 5 MiB. Or we could look at the time between downloading 0.5 MiB to 1 MiB
 that we have data for from our 1 MiB and 5 MiB downloads.

 The ask was to plot nearly worst-case bandwidth. So, my guess is that we
 shouldn't plot the minimum, because we'd only be looking at outliers, but
 instead the 1st or 5th or 10th percentile. Let's maybe start with the 1st
 percentile.

 I'm attaching two graphs for the public server case and the onion server
 case. They both show the respective 1st percentile bandwidth of successful
 1 MiB and 5 MiB downloads on a given day.

 The coding and deployment effort for bringing this graph on the Tor
 Metrics website would be comparatively small, because we already have all
 required data in the database. However, I'm not attaching a patch yet,
 because I'd first want to discuss the general idea of having such a graph.

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