Re: [Haskell-cafe] Performance of concurrent array access

Thanks for the suggestions. I tried to add strictness in the following ways: (1) Changing "insertDAT a j c" to "insertDAT a j $! c" (2) Changing "insertDAT a j c" to "deepseq c (insertDAT a j c)" I also used Int instead of Int32 throughout and changed the DAT data type to a newtype definition. These changes improved the performance slightly, but still, the multithreaded runs perform significantly worse than the single-threaded runs, by about the same amount (i.e. 0.5 seconds more for the 2 core run than for the 1 core run). I used ghc 7.0.3 for the performance measurements I gave in my message. I've also tried under 7.2.1, and I get basically the same behavior there. --Andreas On Tue, Aug 23, 2011 at 4:38 PM, Johan Tibell wrote:

On Tue, Aug 23, 2011 at 10:04 PM, Andreas Voellmy wrote:

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data DAT = DAT (IOArray Int32 Char)

Try to make this a newtype instead. The data type adds a level of indirection.

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do let p j c = insertDAT a j c >> lookupDAT a j >>= \v -> v `pseq` return ()

You most likely want (insertDAT a j $! c) to make sure that the element is force, to avoid thunks building up in the array.

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-- Parameters arraySize :: Int32

Int might work better than Int32. While they should behave the same on 32-bit machines Int might have a few more rewrite rules that makes it optimize better.

-- Johan