[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:  reopened
 Priority:  Medium         |      Milestone:  sbws 1.0 (MVP must)
Component:  Core Tor/sbws  |        Version:
 Severity:  Normal         |     Resolution:
 Keywords:                 |  Actual Points:
Parent ID:                 |         Points:
 Reviewer:                 |        Sponsor:
---------------------------+-------------------------------------
Changes (by starlight):

 * status:  closed => reopened
 * cc: starlight@… (added)
 * resolution:  implemented =>
 * parent:  #27108 =>


Comment:

 The chosen approach suffers from severe non-linear steps between round
 values:

 {{{
 100000 -> 110000 +10.0%
  40000 ->  41000  +2.5%
 }}}

 The proper way to accomplish this is to round by taking the natural
 log of the value, round that to the nearest 1/20th for uniform
 5% steps and then raise e by the result:

 {{{
 100000 rounds to  98716
 105000 rounds to 103777
 98716 -> 103777 +5.1%

 40000 rounds to 40135
 42000 rounds to 42193
 40135 -> 42193 +5.1%

 1100 rounds to 1096
 1050 rounds to 1043
 1043 -> 1096 +5.1%
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27337#comment:9>
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