[tor-bugs] #25265 [Core Tor/Chutney]: Set consensus parameter CircuitPriorityHalflife to enable the EWMA circuit policy

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#25265: Set consensus parameter CircuitPriorityHalflife to enable the EWMA circuit
policy
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     Reporter:  dgoulet           |      Owner:  (none)
         Type:  defect            |     Status:  new
     Priority:  Medium            |  Milestone:
    Component:  Core Tor/Chutney  |    Version:
     Severity:  Normal            |   Keywords:
Actual Points:                    |  Parent ID:
       Points:                    |   Reviewer:
      Sponsor:                    |
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 So turns out that Chutney is not using EWMA policy at all for circuit
 priority which means that its been using the default policy which is round
 robin.

 I found this by working on a patch that for testing was assert()ing on the
 `cmux->policy` and it exploded.

 See `cell_ewma_set_scale_factor()` on how the EWMA policy is
 enabled/disabled.

 The real network sets: `CircuitPriorityHalflifeMsec 30000`

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25265>
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