[tor-bugs] #27790 [Core Tor/sbws]: sbws: design and construct bias curves

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#27790: sbws: design and construct bias curves
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     Reporter:  teor           |      Owner:  (none)
         Type:  defect         |     Status:  new
     Priority:  Medium         |  Milestone:  sbws 1.1
    Component:  Core Tor/sbws  |    Version:
     Severity:  Normal         |   Keywords:
Actual Points:                 |  Parent ID:  #27346
       Points:                 |   Reviewer:
      Sponsor:                 |
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 From https://trac.torproject.org/projects/tor/ticket/25687#comment:13

 The essence of Torflow's active approach is that observed bandwidth
 capacity at each relay is the key measurement and that it can only be
 reliably determined locally but that it requires adjustment, principally
 to account for used vs unused capacity and secondly the relative
 performance of each node in the asymmetric domain of internet traffic
 routing. IMO indisputably correct. The Peerflow paper tacitly recognizes
 this.

 However the simple linear adjustment algorithm cannot be fine-tuned for
 better results across the vast range of relay performance. IIRC polynomial
 equations of sufficient order can describe curves of near arbitrary
 complexity and therefore parameterized polynomials can be used
 interactively, in a gradual empirical search, to describe an improving set
 of adjustment biases for applying scanner measurements to advertised
 bandwidths. This link illustrates the general principal, though the idea
 is to design and construct bias curves with polynomials rather then to fit
 them somehow.

 ​https://en.wikipedia.org/wiki/Polynomial_regression

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