[tor-bugs] #5755 [Onionoo]: Atlas could show "fraction of Tor network by weight" graphs over time?

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#5755: Atlas could show "fraction of Tor network by weight" graphs over time?
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 Reporter:  arma         |          Owner:  karsten 
     Type:  enhancement  |         Status:  assigned
 Priority:  normal       |      Milestone:          
Component:  Onionoo      |        Version:          
 Keywords:               |         Parent:          
   Points:               |   Actualpoints:          
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Comment(by karsten):

 Replying to [comment:13 mikeperry]:
 > It sounds like you're doing it right, though if you hardcoded Wge and
 Wgm at 0, be aware that they're only 0 now because exits are scarce
 relative to Guard capacity.

 Hmm, can we even pick a relay without the Guard flag for the guard
 position?

 It took me a bit longer to decide on hard-coding Weg and Wem to 0.  There
 might be relays with weird exit policies which don't have the Exit flag,
 but which could be selected for the exit position.  On the other hand,
 it's just too weird to see a relay with reject *:* that has a non-zero
 probability for being picked as exit.  But I don't know if hard-coding the
 weights to 0 is a good idea here.  It's a simple solution, though. :)

 > I'd probably need to see the equations you used to produce those P_*
 values to be sure, actually.

 I just cleaned up and committed the Java code that I used to produce the
 P_* values.  You'll probably be interested in the part beginning
 [https://gitweb.torproject.org/metrics-
 tasks.git/blob/HEAD:/task-5755/src/CalculatePathSelectionProbabilities.java#l174
 in line 174].

 > Also, during his guard research, Tariq discovered that Family lines have
 a rather substantial effect on node selection probabilities. The
 conditional probability of choosing additional nodes once certain families
 are selected for other nodes varies dramatically by family, apparently...
 But that's perhaps not worth worrying about for this ticket.

 I noticed that there are quite a few influences on path selection which we
 can't model.  I ran a modified client that prints out some details about
 its path-selection decisions.  At times, it picked a relay from less than
 half of the relays in the network (though it had descriptors for all of
 them).  I didn't investigate reasons for disregarding all the other
 relays.  It could be families, /16's, or anything else.  I guess what I'm
 looking here is an average probability, preferably one that can be
 computed rather easily from looking at the consensus only.  Also, I'd like
 to use whatever P_guard and P_exit we come up with for the network
 diversity calculation in #6232.

 Thanks!

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5755#comment:14>
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