That looks great! I wonder what about Mac OS leads to such good performance...
Now if only we could get a nice x86_64-producing GHC for Mac OS too, I could use all my RAM and the extra registers my Mac Pro gives me :) On Sat, Apr 18, 2009 at 2:39 PM, Dave Bayer <ba...@cpw.math.columbia.edu> wrote: > I'm a huge fan of the recent paper > > http://ghcmutterings.wordpress.com/2009/03/03/new-paper-runtime-support-for-multicore-haskell/ > > which put me over the top to get started writing parallel code in Haskell. > Parallel code is now integral to my and my Ph.D. students' research. For > example, we recently checked an assertion for the roughly 69 billion atomic > lattices on six atoms, in a day rather than a week, using perhaps 6 lines of > parallel code in otherwise sequential code. When you're anxiously waiting > for the answer, a day is a lot better than a week. (The enumeration itself > is down to two hours on 7 cores, which astounds me. I see no reason to ever > use another language.) > > In that paper, they routinely benchmark N-1 cores on an N core Linux box, > because of a noticeable falloff using the last core, which can do more harm > than good. I had confirmed this on my four core Linux box, but was puzzled > that my two core MacBook showed no such falloff. Hey, two cores isn't > representative of many cores, cache issues yada yada, so I waited. > > I just got an EFi-X "boot processor" (efi-x.com) working on a nearly > identical quad core box that I built, and I tested the same computations > with OS X. For my test case, there's a mild cost to moving to parallel at > all, but... > > Compared to 2 cores, using 3, 4 cores on a four core Linux box gives > speedups of > > 1.37x, 1.38x > > Compared to 2 cores, using 3, 4 cores on an equivalent four core box running > OS X gives speedups of > > 1.45x, 1.9x > > Here 1.5x, 2.0x is ideal, so I'm thrilled. If we can't shame Linux into > fixing this, I'm never looking back. How true is this for other parallel > languages? Haskell alone is perhaps too fringe to cause a Linux scandal over > this, even if it should... > > The EFi-X boot processor itself is rather expensive ($240 now), and there's > sticking to a specific hardware compatibility list, and I needed to update > my motherboard BIOS and the EFi-X firmware, but no other fiddling for me. > These boxes are just compute servers for me, I would have been ok returning > to Linux, but not if it means giving up a core. People worry about > compatibility, "I sensed a softness in the surround sound in game X...", but > for me the above numbers put all this in perspective. > > Another way to put this, especially for those who don't have a strong > preference for building their own machines, and can't wait for Linux to get > its act together: > > If you're serious about parallel Haskell, buy a Mac Pro. > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users