[tor-bugs] #27337 [Core Tor/sbws]: Round relay bandwidths in bandwidth files

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#27337: Round relay bandwidths in bandwidth files
---------------------------+-------------------------------------
 Reporter:  teor           |          Owner:  (none)
     Type:  defect         |         Status:  new
 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 juga):

 Replying to [ticket:27337 teor]:
 > Torflow rounds raw bandwidths to 3 significant figures, and increases 0
 bandwidths to 1:
 >
 >
 https://gitweb.torproject.org/torflow.git/tree/NetworkScanners/BwAuthority/aggregate.py#n62

 ah, i've being wondering why that

 > === Rounding ===
 >
 > sbws must round to 3 (or fewer) significant figures, so that consensus
 diffs are still efficient.
 >
 > I suggest 2 significant figures, because the largest error is 5% at
 1.5*10^n^ (for example: (105-100)/100 = 5%).

 ok, will implement this

 > Bandwidth authorities already vary from each other by 25-50%:
 > https://trac.torproject.org/projects/tor/ticket/25459#comment:5
 >
 > And network load varies each day (from what I remember, my guards and
 exits used to vary by at least 10% every day).
 >
 > === Avoiding Zeroes ===
 >
 > I think sbws should also increase 0 bandwidths to 1.

 hmm, which one of the bandwidth values?. So far the we round all decimal
 values and take max(value, 1). The only bandwidth that can still be 0 is
 the descriptor observed bandwidth, that's it's also rounded and take min 1
 after it's multiplied by the ratio. Should the descriptor observed
 bandwidth be at least 1 before multiplying by the ratio?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27337#comment:4>
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