[tor-bugs] #7707 [Tor]: Impose a minimum write size for TLS writes

[Tor Bug Tracker & Wiki]

#7707: Impose a minimum write size for TLS writes
-------------------------+-------------------------------------------------
     Reporter:  nickm    |      Owner:
         Type:  defect   |     Status:  needs_information
     Priority:  normal   |  Milestone:  Tor: 0.2.5.x-final
    Component:  Tor      |    Version:
   Resolution:           |   Keywords:  tor-relay performance bwbug
Actual Points:           |  024-backport
       Points:           |  Parent ID:
-------------------------+-------------------------------------------------

Comment (by arma):

 What are we hoping to learn from the TLS write overhead stats? Some relay
 operators like Jens report stats like 13%. On moria5 run now it's 8%. On
 moria1 lately it's 4%.

 It seems like 4% is a good number, but 13% is a high number.

 Or to give a more useful question: what TLS write overhead do we expect if
 we're always putting each 512-byte cell in its own TLS record? Which SSL's
 do the "empty record" trick still, and I assume that adds to this per-cell
 overhead?

 Does the TLS overhead we're counting here mush together both the overhead
 from normal TLS records and also the overhead from TLS handshakes?

 And finally, once we know what overhead percentage range we're hoping for,
 we should ask relay operators to tell us if they see anything out of that
 range -- or even turn that into an LD_BUG or something.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/7707#comment:15>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online