[GHC] #991: -O option doesn't deal with par well

[GHC]

#991: -O option doesn't deal with par well
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 Reporter:  shelarcy at capella.freemail.ne.jp  |          Owner:         
     Type:  bug                              |         Status:  closed 
 Priority:  normal                           |      Milestone:         
Component:  Compiler                         |        Version:  6.6    
 Severity:  normal                           |     Resolution:  fixed  
 Keywords:  Parallel Haskell                 |     Difficulty:  Unknown
 Testcase:                                   |   Architecture:  Unknown
       Os:  Unknown                          |  
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Changes (by simonmar):

  * resolution:  => fixed
  * status:  new => closed

Comment:

 The warnings are harmless; I've fixed it now anyway.

 As for making the program slower, any number of things might be causing
 this.  Firstly you should be aware that the fixity of `par` in 6.6 is
 wrong (see my recent msg to glasgow-haskell-users about this).  Secondly,
 make sure that the granularity of the computations you intend to
 parallelise is large enough: there's no point trying to spark a single
 multiplication in parallel, for example.  The mailing list is a better
 place to continue discussing this, until we establish whether there's a
 real bug.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/991>
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