[Haskell-cafe] Slow IO?
stevech1097 at yahoo.com.au
Tue Sep 1 23:55:41 EDT 2009
On Tue, 2009-09-01 at 08:45 +0400, Eugene Kirpichov wrote:
> Hm, on my machine Don's code has exactly the same performance my code above.
> Also, replacing the 'test' and 'parse' functions with this one
> add :: Int -> Int -> S.ByteString -> Int
> add k i s = fst $ S.foldl' f (i, 0) s
> where f (!i, !n) '\n' | n`divisibleBy`k = (i+1, 0)
> | otherwise = (i, 0)
> f (!i, !n) w = (i, 10*n+ord w-ord '0')
> increases performance by another 15% (0.675s vs 0.790s)
On my system I get a 50% slowdown using this add function!
I guess is just shows that benchmarking code on one single
CPU/memory/OS/ghc combination does not give results that apply widely.
AMD Athlon X2 4800
Linux (Fedora 11, 64-bit version)
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