Hrm, Okay, it seems that my problems maybe be due to using ghc 6.3. Here are the results of running test under different compiler versions (see end of message for code): Athlon 600MHz + FreeBSD + GHC 6.0.1 real 0m0.414s user 0m0.361s sys 0m0.016s Athlon 600MHz + FreeBSD + GHC 6.3 (built from CVS HEAD on Feb 15, 2004) real 0m2.517s user 0m2.289s sys 0m0.069s Pentium III 1.13GHz + Debian + GHC 6.2 real 0m0.305s user 0m0.196s sys 0m0.027s Pentium III 1.13GHz + Debian + GHC 6.3 (built from CVS HEAD on Feb 1, 2004) real 0m1.302s user 0m1.196s sys 0m0.044s So it seems like maybe GHC 6.3's performance for this particular test is around 3-5 slower? Jeremy Shaw. module Main where import Data.Array import Data.Array.IO import System.IO main = do h <- openFile "test.b" WriteMode a <- newArray_ (1,1800000) b <- mapArray id a c <- mapArray id b hPutArray h c 1800000 At Mon, 23 Feb 2004 13:37:45 -0800, Mike Gunter wrote:
Hmmm. With -O2 on GHC 6.2, I get 0.177s, 0.217s, and 0.348s for your three Haskell examples and 0.187s (with gcc -O2) for your C example. The output of -ddump-simpl for the looks perfect for the second Haskell example. My GHC seems to be doing a bang-up job here. What's wrong with yours? (For the third example GHC's code could be improved by additional inlining or hoisting of a constant array outside of the loop.)
mike