[tor-bugs] #33009 [Core Tor/sbws]: sbws bandwidth scans should require a minimum exit bandwidth

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#33009: sbws bandwidth scans should require a minimum exit bandwidth
------------------------------------------------+--------------------------
 Reporter:  teor                                |          Owner:  (none)
     Type:  defect                              |         Status:  new
 Priority:  Medium                              |      Milestone:  sbws:
                                                |  1.1.x-final
Component:  Core Tor/sbws                       |        Version:  sbws:
                                                |  1.1.0
 Severity:  Normal                              |     Resolution:
 Keywords:  sbws-majority-blocker, easy, intro  |  Actual Points:
Parent ID:                                      |         Points:  1
 Reviewer:                                      |        Sponsor:
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Changes (by teor):

 * keywords:  sbws-majority-blocker => sbws-majority-blocker, easy, intro


Comment:

 Note: Torflow's partitions have a similar issue, but it's actually worse:
 a relay can get stuck in a low-bandwidth partition forever.

 So perhaps this isn't strictly a blocker, because the new behaviour is
 eventually better. But the fix is so easy, we should just do it.

 I suggest we only use the top 75% of exits as the second hop, which should
 remove the long tail of slow exits. (These slow exits are also more likely
 to fail to connect, and therefore fail the entire bandwidth test. So this
 change should also improve sbws efficiency.)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33009#comment:1>
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