[GHC] #8733: I/O manager causes unnecessary syscalls in send/recv loops

[GHC]

#8733: I/O manager causes unnecessary syscalls in send/recv loops
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        Reporter:  tibbe                    |            Owner:  simonmar
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:  7.10.1
       Component:  Runtime System           |          Version:  7.6.3
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Comment (by schyler):

 If I understand correctly, this can be implemented as a state machine.
 Each thread can have a "last IO action" state which gets reset when it
 yields and set to some constant on send/recv. Then, if you call recv and
 it's still in send mode, yield automatically (and yield would set it back
 to NULL).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8733#comment:8>
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