[GHC] #367: Infinite loops can hang Concurrent Haskell

[GHC]

#367: Infinite loops can hang Concurrent Haskell
------------------------------------------+---------------------------------
  Reporter:  simonpj                      |          Owner:  ezyang              
      Type:  bug                          |         Status:  new                 
  Priority:  lowest                       |      Milestone:  _|_                 
 Component:  Compiler                     |        Version:  6.4.1               
Resolution:  None                         |       Keywords:  scheduler allocation
        Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple    
   Failure:  Incorrect result at runtime  |     Difficulty:  Unknown             
  Testcase:                               |      Blockedby:                      
  Blocking:                               |        Related:                      
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Comment(by ezyang):

 Here are the aggregate stats for the stack check version (overall, it
 seems that it produces more bloated executables, but is a little bit
 faster):

 {{{
 --------------------------------------------------------------------------------
         Program           Size    Allocs   Runtime   Elapsed  TotalMem
 ----------------------------------------------------------------------------
             Min          +6.1%     -0.1%     -7.2%     -6.7%    -50.0%
             Max          +6.7%     +5.8%     +5.9%     +6.1%     +0.8%
  Geometric Mean          +6.6%     +0.1%     +0.1%     +0.2%     -0.8%
 }}}

 Switching to stack checks has some interesting interactions with some of
 the optimizations; for example, we can no longer optimize away Sp - 0 <
 SpLim as true, since SpLim may have been twiddled with. If we run nofib
 without adding the extra yields but with those optimizations turned off,
 we see:

 {{{
             Min          +5.9%     -0.1%     -7.3%     -7.0%    -50.0%
             Max          +6.7%     +5.8%     +3.9%     +4.1%     +0.0%
  Geometric Mean          +6.6%     +0.1%     -0.1%     -0.1%     -0.8%
 }}}

 So we already pay most of the cost from having to ditch the optimizations.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/367#comment:25>
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