[tor-bugs] #3338 [Analysis]: Why do our user graphs have these huge spikes?

Tor Bug Tracker & Wiki torproject-admin at torproject.org
Fri Jun 24 18:43:38 UTC 2011


#3338: Why do our user graphs have these huge spikes?
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 Reporter:  arma      |          Owner:     
     Type:  task      |         Status:  new
 Priority:  normal    |      Milestone:     
Component:  Analysis  |        Version:     
 Keywords:            |         Parent:     
   Points:            |   Actualpoints:     
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Comment(by karsten):

 It looks like the directory bytes estimate isn't that bad.  The problem is
 just that we don't have enough directory mirrors reporting directory-
 request statistics to us.  See the attached graph dir-bytes-estimate.pdf
 for the details.

 The blue line shows the extrapolated directory byte metric for all
 directory mirrors.  This line should be pretty reliable except for the
 first few days in August 2010 when only a few directory mirrors reported
 directory bytes.  But we cannot use this line, because it only reaches
 back to August 2010 and we want user statistics since August 2009.

 The red line is our directory byte estimate based on the difference
 between written and read total bytes.  I would have expected a bigger
 distance from the blue line or a much higher volatility.  But great, in
 theory, the estimate still works fine.

 Now, the green line is the same estimate, but only for directory mirrors
 reporting directory request statistics.  We use the quotient of the red
 and green line to compute our "fraction" in the other graph.  I marked the
 same four points with purple dots when our user number skyrocketed.

 My conclusion would be that there need to be more and faster directory
 mirrors reporting directory request statistics than on those four days.
 If we reach around 1/3 or 1/2, bandwidth-wise, of directory mirrors
 reporting directory request statistics, we should do okay.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/3338#comment:14>
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