[tor-bugs] #22798 [Core Tor/Tor]: Windows relay is several times slower than Linux relay

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#22798: Windows relay is several times slower than Linux relay
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 Reporter:  Vort                           |          Owner:
     Type:  defect                         |         Status:  new
 Priority:  Medium                         |      Milestone:  Tor:
                                           |  unspecified
Component:  Core Tor/Tor                   |        Version:  Tor: 0.2.9.11
 Severity:  Normal                         |     Resolution:
 Keywords:  tor-relay performance windows  |  Actual Points:
Parent ID:                                 |         Points:  5
 Reviewer:                                 |        Sponsor:
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Comment (by cypherpunks):

 https://msdn.microsoft.com/en-
 us/library/windows/desktop/bb736549(v=vs.85).aspx seems like solution to
 implement really working send buffer auto-tuning:
 {{{
 Applications that perform one blocking or non-blocking send request at a
 time typically rely on internal send buffering by Winsock to achieve
 decent throughput. The send buffer limit for a given connection is
 controlled by the SO_SNDBUF socket option. For the blocking and non-
 blocking send method, the send buffer limit determines how much data is
 kept outstanding in TCP. If the ISB value for the connection is larger
 than the send buffer limit, then the throughput achieved on the connection
 will not be optimal. In order to achieve better throughput, the
 applications can set the send buffer limit based on the result of the ISB
 query as ISB change notifications occur on the connection.
 }}}
 On every connection_handle_write_impl() or somewhere yet, to query, to
 count, to set optimal value for SO_SNDBUF
 Not so much code, but seems like for Win7 only.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22798#comment:48>
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