[tor-bugs] #28442 [Core Tor/sbws]: sbws does not round bandwidths to 2 significant figures

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#28442: sbws does not round bandwidths to 2 significant figures
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     Reporter:  teor           |      Owner:  teor
         Type:  defect         |     Status:  assigned
     Priority:  Medium         |  Milestone:  sbws 1.0 (MVP must)
    Component:  Core Tor/sbws  |    Version:
     Severity:  Normal         |   Keywords:
Actual Points:                 |  Parent ID:
       Points:                 |   Reviewer:
      Sponsor:                 |
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 sbws currently rounds bandwidths to the nearest 1000. (Bandwidths under
 500 are rounded to 1.)

 This creates large errors in relay bandwidths:
 * max(round(499, -3), 1) = 1
 * max(round(500, -3), 1) = 1000
 * max(round(1499, -3), 1) = 1000

 But torflow rounds bandwidths to 3 significant figures:
 https://gitweb.torproject.org/torflow.git/tree/NetworkScanners/BwAuthority/aggregate.py#n62

 And proposal 276 says to round to 2 significant figures, with some extra
 rounding of the final non-zero digit:
 https://gitweb.torproject.org/torspec.git/tree/proposals/276-lower-bw-
 granularity.txt#n36

 This is a bug on #27337.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28442>
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