#7850: Strangely high memory usage on optimized Ackermann function ---------------------------------+------------------------------------------ Reporter: dolio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.2 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: Runtime performance bug Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ Comment(by awson): Most interesting is that while many notice `-kc1M` cure the problem they still insist it runs much slower than Ocaml version. But it is *NOT*! It takes less than 6.5 secs to deliver a correct answer for original unmodified version of ack with `-kc1M` on all my configs: Windows 8 64-bit on Q9450 2.66MHz:[[BR]] ghc-7.6.2 32-bit - 6.49 secs[[BR]] ghc-7.6.2 64-bit - 6.47 secs Windows 7 on i7-2675QM[[BR]] ghc-7.6.2 32-bit - 6.13 secs[[BR]] ghc-7.6.2 64-bit - 3.80 (!!!) secs (i tried this several times with the same result) Could it be GHC RTS on Windows which makes the difference? -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7850#comment:24 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler