On April 21, 2009 04:39:40 Simon Marlow wrote:
These ratios match up like physical constants, or at least invariants of my Haskell implementation. However, the user time is constant on OS X, so these ratios reflect the actual parallel speedup on OS X. The user time climbs steadily on Linux, significantly diluting the parallel speedup on Linux. Somehow, whatever is going wrong in the interaction between Haskell and Linux is being captured in this increase in user time.
We can't necessarily blame this on Linux: the two machines have different hardware. There could be cache-effects at play, for example.
Why not try booting a CD or thumb-drive linux distro (e.g., ubuntu live) on your 2.4 GHz Q6600 OS X box and see how things stack up. It would certainly eliminate any questions of hardware differences. Cheers! -Tyson