On Wed, Aug 5, 2009 at 6:59 PM, Thomas Witzel <witzel.tho...@gmail.com>wrote: > > > 2. I started with the very simple nfib example given in the manual for > Control.Parallel (Section 7.18). On my systems using multiple cores > makes the code actually slower than just using a single core. While > the manual cautions that this could be the case for certain > algorithms, I'm wondering whether this is the desired behaviour for > this example. > > I'm using ghc 6.10.4 right now. >
IIRC the development version of GHC has some major work to optimize concurrency, so it may be worth trying that. In particular I believe it executes sparks in batches, to reduce the overhead (which hopefully fixes your issue). -- Sebastian Sylvan
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