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

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#17544: Our SipHash-2-4 performance is sometimes odd.
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     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:
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 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.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17544>
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