#8027: Adding one call to getNumCapabilities triggers performance nose dive (6X
slowdown)
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Reporter: rrnewton | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Runtime System | Version: 7.6.3
Resolution: wontfix | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Runtime performance bug | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Changes (by rrnewton):
* status: new => closed
* resolution: => wontfix
Comment:
Ah... my mistake. What was so apparently baffling is actually pretty
reasonable.
In this case adding more code to the function simply changes inlining
decisions, which in turn determines whether dictionary elimination can be
done. The 6X performance difference is just because of that.
Perhaps such a function should be monomorphic to be safe... since the
difference is so big.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/8027#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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