Bulat,
The strictness gave me something like a 10% performance increase
making the Haskell code more than 10 times slower than the C. Is this
the right type of array to use for performance?
--
Dan
On Nov 8, 2007 10:36 AM, Bulat Ziganshin
Hello Dan,
Thursday, November 8, 2007, 9:33:12 PM, you wrote:
main = do a <- newArray (0,n-1) 1.0 :: IO (IOUArray Int Double) forM_ [0..n-2] $ \i -> do { x <- readArray a i; y <- readArray a (i+1); writeArray a (i+1) (x+y) } x <- readArray a (n-1) print x
1. ghc doesn't implement loop unrolling, even in -O2 mode 2. forM_ may have its own overheads, i'm not sure 3. add strictness annotations:
forM_ [0..n-2] $ \i -> do { return $! i; x <- readArray a i; return $! x; y <- readArray a (i+1); return $! y; writeArray a (i+1) (x+y) }
such cycle should be approx. 3-10 times slower than C one
-- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com