[GHC] #4965: 60% performance regression in continuation-heavy code between 6.12 and 7

[GHC]

#4965: 60% performance regression in continuation-heavy code between 6.12 and 7
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    Reporter:  bos               |        Owner:                         
        Type:  bug               |       Status:  new                    
    Priority:  high              |    Milestone:  7.2.1                  
   Component:  Compiler          |      Version:  7.0.1                  
    Keywords:                    |     Testcase:                         
   Blockedby:                    |   Difficulty:                         
          Os:  Unknown/Multiple  |     Blocking:                         
Architecture:  Unknown/Multiple  |      Failure:  Runtime performance bug
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Comment(by bos):

 I've attached two heap profile outputs, one generated with 6.12.3 and
 another with 7.0.3, both 32-bit.

 For this particular test case (an 8.3MB JSON file), 6.12.3 is about 66%
 faster than 7.0.3, and uses a little over half the memory. It looks like
 the 22% performance difference only applies to small inputs. The larger
 the input, the bigger the advantage that 6.12.3 has.

 64-bit GHC 7.0.3 uses almost 300MB of heap here, which is pretty painful.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4965#comment:11>
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