[tor-bugs] #27135 [Core Tor/sbws]: Write descriptor bandwidths average in raw results

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#27135: Write descriptor bandwidths average in raw results
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 Reporter:  juga           |          Owner:  juga
     Type:  defect         |         Status:  assigned
 Priority:  Medium         |      Milestone:  sbws 1.0 (MVP must)
Component:  Core Tor/sbws  |        Version:
 Severity:  Normal         |     Resolution:
 Keywords:                 |  Actual Points:
Parent ID:  #27108         |         Points:
 Reviewer:                 |        Sponsor:
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Comment (by pastly):

 Replying to [comment:7 teor]:
 > Replying to [comment:5 pastly]:
 > > I downloaded your sbws datadir and wrote a little script to print how
 often a relay has a list of saved `relay_average_bandwidth` containing
 more than one unique element.
 > >
 > > It found that 1868/7999 relays had `relay_average_bandwidth` values
 that weren't all the same (118/7326 if you only look at success results).
 I'm guessing relays don't update this value in their descriptors very
 often.
 >
 > I don't know the period covered by juga's sbws datadir. But these
 figures seem reasonable for a few hours' consensuses: 1/18 * 7999 = 444.
 >
 > If the datadir covers days, maybe sbws is losing descriptor updates?

 It covered days. Like maybe a week. I think the issue is that sbws only
 records a relay's current descriptor bandwidth when it is recording a
 measurement for it, which happens **very** roughly once a day (this is not
 a parameter that can be directly tuned, it depends on many things like
 number of measurement threads and target download length). So yes sbws is
 losing descriptor updates, because I/we/it never knew they were that
 important to begin with!

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27135#comment:8>
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