[tor-bugs] #17544 [Tor]: Our SipHash-2-4 performance is sometimes odd.

["Tor Bug Tracker & Wiki" <blackhole@xxxxxxxxxxxxxx>]

#17544: Our SipHash-2-4 performance is sometimes odd.
-------------------------+-----------------------------------
     Reporter:  yawning  |      Owner:
         Type:  defect   |     Status:  new
     Priority:  Low      |  Milestone:  Tor: 0.2.8.x-final
    Component:  Tor      |    Version:  Tor: 0.2.5.10
     Severity:  Normal   |   Keywords:  tor-core, performance
Actual Points:           |  Parent ID:
       Points:           |    Sponsor:
-------------------------+-----------------------------------
 Something is screwed up (probably in the code gen), such that hashing
 buffers that aren't a multiple of 8 has performance issues.

 {{{
 siphash24g(7): 30.42 ns per call
 siphash24g(8): 22.67 ns per call
 siphash24g(15): 34.08 ns per call
 siphash24g(16): 27.14 ns per call
 siphash24g(20): 36.35 ns per call
 siphash24g(32): 37.66 ns per call
 siphash24g(111): 93.87 ns per call
 siphash24g(128): 100.21 ns per call
 }}}

 I'm not sure if deviating from the upstream further to fix this is the
 right thing to do, but we probably call this code a decent amount.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17544>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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