[tor-bugs] #33871 [Core Tor/sbws]: Scale exactly as torflow does?

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#33871: Scale exactly as torflow does?
-------------------------------------------------+-------------------------
 Reporter:  juga                                 |          Owner:  juga
     Type:  defect                               |         Status:
                                                 |  assigned
 Priority:  Medium                               |      Milestone:  sbws:
                                                 |  1.1.x-final
Component:  Core Tor/sbws                        |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  sbws-majority-blocker, sbws-roadmap  |  Actual Points:
Parent ID:  #33775                               |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by juga):

 Replying to [comment:15 juga]:
 [snip]
 > > I just dug a bit deeper into the 0 bw issue, and I found that we
 actually set it to at leasty 1, to simplify computation. This is done in
 the TorCtl.Router class:
 https://gitweb.torproject.org/pytorctl.git/tree/TorCtl.py#n379
 > >
 > > So we should probably do something that in sbws too (either hack to 1
 or riddle with special cases everywhere), so we can still measure 0-bw
 relays.
 >
 > Yes, we're doing that in sbws, note that in my previous reply i included
 a `1` in the `new_bw` equations, ie. `new_bw = min(consensus bandwidth,
 descriptor observed bandwidth, descriptor average bandwidth, descriptor
 burst bandwidth, 1) * ratio`

 Oh, sorry, i wanted to put all in 1 line, but this ^ would be always `1`
 :)
 So it should be the maximum between any bandwidth value and 1 and then the
 minimum with those.
 I realized that we're actually taking the maximum of the new bandwidth and
 1 at the very end, which would be also different to take the maximum of
 any bandwidth value an 1 before multiplying by the ratio. We should
 probably do it in this last way, as torflow does.

 >
 > What i mean is that it's a different thing to calculate the minimum when
 one of those values is 0 (the result will be 1) or to exclude one of those
 values when it's 0 (the result will be greater or equal than 1).
 >
 > Note that AFAIU, Torflow code is not calculating the `new_bw` using the
 consensus bandwidth, though, it just does not produce any bandwidth file
 if any consensus bandwidth is missing.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33871#comment:16>
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