Denis Bueno wrote:
It would be much easier to draw sound conclusions if you would post your code.
Erm... good point. See attachments. module Sort where import Control.Parallel import Control.Parallel.Strategies split0 [] = [] split0 (x:xs) = x : split1 xs split1 [] = [] split1 (x:xs) = split0 xs merge xs [] = xs merge [] ys = ys merge (x:xs) (y:ys) | x < y = x : merge xs (y:ys) | otherwise = y : merge (x:xs) ys msort [] = [] msort [x] = [x] msort xs = let xs0 = msort (split0 xs) xs1 = msort (split1 xs) in merge xs0 xs1 msortP [] = [] msortP [x] = [x] msortP xs = let xs0 = msort (split0 xs) xs1 = msort (split1 xs) in seqList rwhnf xs0 `par` seqList rwhnf xs1 `seq` merge xs0 xs1 list = [5,4,6,3,7,2,8,1,9,0] module Time where import System.CPUTime time :: IO () -> IO Integer time fn = do t0 <- getCPUTime fn t1 <- getCPUTime return (t1 - t0) ps_ms = 1000000000 :: Integer ps_s = ps_ms * 1000 :: Integer module Main where import Data.Word import System.IO import GHC.Conc (numCapabilities) import Sort import Time type Test = (String,[Word32]) random = iterate (\x -> 1664525 * x + 1013904223) 7 :: [Word32] test1m = ("1M",take 1000000 random) test2m = ("2M",take 2000000 random) type Algo = (String, [Word32] -> [Word32]) algo_seq_msort = ("MergeSortSeq", msort) algo_par_msort = ("MergeSortPar", msortP) dump :: [Word32] -> String dump = unlines . map show run_tests :: Algo -> Test -> IO () run_tests (name,fn) (title,xs) = do echo "\n" let f1 = name ++ "--" ++ title ++ "--In.txt" echo $ "Writing '" ++ f1 ++ "'..."; hFlush stdout nullT <- time (writeFile f1 (dump xs)) echo $ " Took " ++ show (nullT `div` ps_ms) ++ " ms.\n" mapM_ (\n -> do let f2 = name ++ "--" ++ title ++ "--Out" ++ show n ++ ".txt" echo $ "Writing '" ++ f2 ++ "'..."; hFlush stdout sortT <- time (writeFile f2 (dump (fn xs))) echo $ " Took " ++ show (sortT `div` ps_ms) ++ " ms.\n" ) [1..8] echo msg = do hPutStr stdout msg hPutStr stderr msg main = do echo $ "CPU threads = " ++ show numCapabilities ++ ".\n" mapM_ (\test -> mapM_ (\algo -> run_tests algo test) [algo_seq_msort, algo_par_msort] ) [test1m, test2m]