[GHC] #8578: Improvements to SpinLock implementation

[GHC]

#8578: Improvements to SpinLock implementation
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        Reporter:  parcs             |            Owner:  parcs
            Type:  task              |           Status:  patch
        Priority:  normal            |        Milestone:
       Component:  Runtime System    |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by simonmar):

 The patch looks like a nice improvement, thanks!  Before committing I want
 to run some benchmarks.  The usual ones I use are `nofib/parallel` running
 on various numbers of cores, at least 8.  I can try these sometimes next
 week.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8578#comment:3>
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