[tor-bugs] #4487 [Analysis]: Research: Does N23 help especially much in cases where the first hop is slow/flaky?

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#4487: Research: Does N23 help especially much in cases where the first hop is
slow/flaky?
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 Reporter:  arma                     |          Owner:       
     Type:  task                     |         Status:  new  
 Priority:  normal                   |      Milestone:       
Component:  Analysis                 |        Version:       
 Keywords:  performance flowcontrol  |         Parent:  #4506
   Points:                           |   Actualpoints:       
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Changes (by robgjansen):

 * cc: jansen@… (removed)
 * cc: robgjansen (added)


Comment:

 Replying to [comment:7 arma]:
 > Results in #4486 show "no, n23 doesn't look like a good idea with the
 parameters we picked, unless there's a bug in the n23 patch or something".
 >
 > Rob, is now a good time to do a run where some of the clients are on
 slow/flaky first hops, and see if n23 looks better in this light?
 >
 > I don't have a good handle on what I mean by 'slow/flaky', so "pick
 whatever definition you like" is my first suggestion.

 I ran 100 of the 2375 web clients as "slow" web clients, configuring their
 access to the rest of the network with 200 millisecond latency, 25 ms
 jitter, and a 15% chance that each packet gets dropped. These nodes were
 given bandwidths of 500 KiB/s down and 200 KiB/s up.

 I again ran vanilla, 'UseN23 1', and 'N3Initial 50' configs.

 The results are
 [https://trac.torproject.org/projects/tor/attachment/ticket/4487/20121115-apollo-n23
 -flaky-combined.pdf in these graphs]. They show a bigger improvement in
 last byte download time for the slow web clients than for the normal web
 clients, matching your intuition. However, overall the performance boost
 is still not what we had hoped.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4487#comment:8>
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