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
<johan.tibell@gmail.com> wrote:
On Tue, Aug 23, 2011 at 10:04 PM, Andreas Voellmy
> data DAT = DAT (IOArray Int32 Char)
Try to make this a newtype instead. The data type adds a level of indirection.
> 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.
> -- 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