[metrics-bugs] #34023 [Metrics/Onionperf]: Kill the 50 KiB downloads

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#34023: Kill the 50 KiB downloads
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     Reporter:  karsten            |      Owner:  metrics-team
         Type:  enhancement        |     Status:  new
     Priority:  Medium             |  Milestone:
    Component:  Metrics/Onionperf  |    Version:
     Severity:  Normal             |   Keywords:
Actual Points:                     |  Parent ID:
       Points:                     |   Reviewer:
      Sponsor:                     |
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 On #33076 we discussed whether we should kill the 50 KiB downloads in
 deployed OnionPerfs and only keep the 1 MiB and 5 MiB downloads. The
 primary reason would be that our [https://metrics.torproject.org
 /onionperf-throughput.html throughput] graphs would be based on five times
 as many data points per day, because they only include 1 MiB and 5 MiB
 downloads, but not 50 KiB downloads. This would not affect our
 [https://metrics.torproject.org/onionperf-latencies.html circuit round-
 trip latencies graphs] which include all three downloaded file sizes.

 The main reason against killing 50 KiB downloads is that OnionPerfs would
 consume more bandwidth and also put more load on the Tor network. Let's
 consider two scenarios with and without 50 KiB downloads. In both
 scenarios we're making a new download every 5 minutes, randomly chosen
 with a weight of 1.0 for 5 MiB runs, 2.0 for 1 MiB runs, and either 12.0
 or 0.0 for 50 KiB runs:

  - With 50 KiB downloads we're downloading on average `12/15 * 50 KiB +
 2/15 * 1 MiB + 1/15 * 5 MiB = 517 KiB` every 5 minutes, or `517 * 8 * 1024
 / (300 * 1000) = 14 kbps`.

  - Without 50 KiB downloads we're downloading on average `2/3 * 1 MiB +
 1/3 * 5 MiB = 2389 KiB` every 5 minutes, or `2389 * 8 * 1024 / (300 *
 1000) = 65 kbps`.

 These numbers are both tiny in comparison to the overall network capacity
 and to other services like the bandwidth scanners.

 I'm going to make this change and deploy it on new OnionPerf instances
 tomorrow, unless I hear objections here.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/34023>
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