[GHC] #8027: Adding one call to getNumCapabilities triggers performance nose dive (6X slowdown)

[GHC]

#8027: Adding one call to getNumCapabilities triggers performance nose dive (6X
slowdown)
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    Reporter:  rrnewton          |       Owner:                         
        Type:  bug               |      Status:  new                    
    Priority:  normal            |   Milestone:                         
   Component:  Runtime System    |     Version:  7.6.3                  
    Keywords:                    |          Os:  Unknown/Multiple       
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
  Difficulty:  Unknown           |    Testcase:                         
   Blockedby:                    |    Blocking:                         
     Related:                    |  
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Comment(by rrnewton):

 UPDATE: I found at least one other way to trigger the bug without calling
 those system functions.  This makes me think its some kind of compiler bug
 (or mis-optimization) rather than a runtime bug.

 I would love to know if anyone else can reproduce this problem...

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/8027#comment:2>
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