[Haskell-cafe] Concurrency performance problem

[Don Stewart]

Depends on your code...
On Mar 4, 2013 6:10 PM, "Łukasz Dąbek" <sznurek at gmail.com> wrote:

> Hello Cafe!
>
> I have a problem with following code: http://hpaste.org/83460. It is a
> simple Monte Carlo integration. The problem is that when I run my
> program with +RTS -N1 I get:
> Multi
> 693204.039020917 8.620632s
> Single
> 693204.039020917 8.574839s
> End
>
> And with +RTS -N4 (I have four CPU cores):
> Multi
> 693204.0390209169 11.877143s
> Single
> 693204.039020917 11.399888s
> End
>
> I have two questions:
>  1) Why performance decreases when I add more cores for my program?
>  2) Why performance of single threaded integration also changes with
> number of cores?
>
> Thanks for all answers,
> Łukasz Dąbek.
>
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