[GHC] #13497: GHC does not use select()/poll() correctly on non-Linux platforms

[GHC]

#13497: GHC does not use select()/poll() correctly on non-Linux platforms
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        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Runtime System    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8684, #12912     |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nh2):

 Reading the aforementioned
 [https://github.com/ghc/ghc/commit/0b79d5cd4687dacf7efd430df7fba9d9a5a5ce32
 #diff-dce00d71def2bd086622a775b0723323R71 commit] in detail, it seems that
 the code currently doesn't do what the code may not follow the intents
 expressed in the comments:

 {{{
 + * The timer interrupt transitions ACTIVITY_YES into
 + * ACTIVITY_MAYBE_NO, waits for RtsFlags.GcFlags.idleGCDelayTime,
 + * and then:
 + *   - if idle GC is no, set ACTIVITY_INACTIVE and wakeUpRts()
 + *   - if idle GC is off, set ACTIVITY_DONE_GC and stopTimer()
 }}}

 [https://github.com/ghc/ghc/blob/380b25ea4754c2aea683538ffdb179f8946219a0/rts/Timer.c#L66
 Code:]

 {{{
           if (RtsFlags.GcFlags.doIdleGC) {
               recent_activity = ACTIVITY_INACTIVE;
 #ifdef THREADED_RTS
           ...
 }}}

 It depends on what `if idle GC is no` (read: `on`) means. In many places I
 have read that idle GC can really only be "on" in the threaded RTS. In
 that case, the code does not implement the comment, as it sets
 `ACTIVITY_INACTIVE` even when we're not in the threaded RTS.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13497#comment:12>
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