Thank you for your help! This solved my performance problem :) Anyway, the second question remains. Why performance of single threaded calculation is affected by RTS -N parameter. Is GHC doing some parallelization behind the scenes?
-- Łukasz Dąbek. 2013/3/4 Don Stewart <[email protected]>: > Apologies, didn't see the link on my phone :) > > As the comment on the link shows, youre accidentally migrating unevaluated > work to the main thread, hence no speedup. > > Be very careful with evaluation strategies (esp. lazy expressions) around > MVar and TVar points. Its too easy to put a thunk in one. > > The strict-concurrency package is one attempt to invert the conventional > lazy box, to better match thge most common case. > > On Mar 4, 2013 7:25 PM, "Łukasz Dąbek" <[email protected]> wrote: >> >> What do you exactly mean? I have included link to full source listing: >> http://hpaste.org/83460. >> >> -- >> Łukasz Dąbek >> >> 2013/3/4 Don Stewart <[email protected]>: >> > Depends on your code... >> > >> > On Mar 4, 2013 6:10 PM, "Łukasz Dąbek" <[email protected]> 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. >> >> >> >> _______________________________________________ >> >> Haskell-Cafe mailing list >> >> [email protected] >> >> http://www.haskell.org/mailman/listinfo/haskell-cafe _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
