forkOS should work as well, assuming you have OS threads, like in linux 2.6. You should probably be using the -smp compiler flag and not the -threaded compiler flag, I'm guessing, and make sure that your +RTS arguments indicate that you want to use X total concurrent threads... -- Jeff On Tuesday 13 March 2007 13:10, Dusan Kolar wrote:
Yes, it works for operator /par/. That's what I've reported. But should it work for forkIO and forkOS? Could anybody give more detailed answer than yes, no? :-) (Link to the Web is OK.)
BTW, thanks for the link to the paper (moreover, I can see, that googling over haskell.org is not sufficient ;-) ).
Regards,
Dusan
Pepe Iborra wrote:
On 13/03/2007, at 17:46, Jefferson Heard wrote:
Simon will probably chime in on it as well, but his paper on the subject is the best there is:
http://research.microsoft.com/~simonpj/Papers/strategies.ps.gz
It does work in GHC 6.6 very nicely. You can try it with the following naive fib function, extracted from the paper mentioned above:
\begin{code} import Control.Parallel import System.Environment import Fib
main = do (x:_) <- getArgs print$ pfib (read x)
pfib 0 = 1 pfib 1 = 1 pfib n = n1 `par` n2 `seq` n1+n2+1 where (n1,n2) = (pfib(n-1), pfib(n-2)) \end{code}
pep:~/code/snippets/Parallelism$ ghc --make -O Main -threaded
pep:~/code/snippets/Parallelism$ time src/Main 33 11405773
real 0m1.444s user 0m1.343s sys 0m0.020s
pep:~/code/snippets/Parallelism$ time src/Main 33 +RTS -N2 11405773
real 0m0.764s user 0m1.367s sys 0m0.030s
Got a speedup of 100%, and didn't use threads at all. Yay!
pepe
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