bf3:
Donald:
Yeah, there's some known low level issues in the code generator regarding heap and stack checks inside loops, and the use of registers on x86.
But note this updated paper, http://www.cse.unsw.edu.au/~chak/papers/CLPKM07.html
Add another core to your machine and it is no longer 4x slower :) Add 15 more cores and its really no longer 4x slower :
Maybe this is yet another newbie stupid question, but do you mean that GHC does automatic multi-threading? (Haskell seems very suitable for that) Otherwise adding an extra core does not really help does it?
No, though that would be nice! You do have to program in a parallel manner, either by using forkIO, Control.Parallel, or parallel arrays. When you do, you have the option of such code scaling up to more cores relatively easily. My advice: starting writing threaded code now, with *lots* of threads, so your program will have the ability to start using +RTS -N16 when you get a new machine :) -- Don