16 Feb
2008
16 Feb
'08
6:06 p.m.
Hi, all! I have strange GHC behavior. Consider the code: import Control.Parallel main = print (o `par` (fromInteger e) / (fromInteger o)) where [e,o] = map sum $ map (`filter` numbers) [even, odd] numbers = [1..10000000] When it compiled without threaded it has 19068 ms to run, 396 Mb total memory in use and %GC time 88.2%, the same with -threaded and +RTS -N1, but with +RTS -N2 it takes only 3806 ms to run, 3 Mb total memory in use and %GC time 8.1%. Why it so? It's a bug or I missed something? I test it on dual-core Athlon X2 4200+ 2Gb running 64bit Gentoo system. gcc 4.2.2 and ghc 6.8.2. -- Ruslan