On Tue, Mar 3, 2009 at 6:41 PM, Don Stewart <d...@galois.com> wrote: > allbery: >> On 2009 Mar 3, at 12:31, mwin...@brocku.ca wrote: >>> In both runs the same computations are done (sequentially resp. >>> parallel), so the gc should be the same. But still using 2 cores is >>> much slower than using 1 core (same program - no communication). >> >> The same GCs are done, but GC has to be done on a single core >> (currently; parallel GC is in development) so you will see a lot more >> lock contention when the GC kicks in. >> > > Assuming he is using GHC 6.10, the parallel GC is enabled by default > when you use -Nn where n > 1. That's is -N4 will use -g4 (4 cores to > collect). So GC should be the same or a little faster. > Further, GHC (6.10 at least) uses one allocation area per thread, meaning there's no contention on allocation.
I'd echo the request to try it with -O2, though. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
