[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)
---------------------------------+------------------------------------------
    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:                    |  
---------------------------------+------------------------------------------

Comment(by rrnewton):

 I checked with GHC 7.4.2 (Mac and Linux) and see an identical behavior --
 same bug.

 (I'm trying to run with 7.7.20130628 but having trouble installing the
 vector package at this moment...)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/8027#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler