[Haskell-cafe] Known Unknowns

[Donald Bruce Stewart]

haskell:
> Joel Koerwer wrote:
> > Don, that's a great little mini tutorial, exactly what I was hoping for.
> > I'm looking forward to learning more tricks.
> > 
> > On an unrelated note, I have an STUArray nbody. I haven't really looked
> > closely at the chris+dons version, but I suspect they amount to doing
> > the same thing. I get commensurate runtimes at least. But I'll post it
> > on the wiki in a while in case there is some optimization I missed.
> > 
> > On an even more unrelated note, I get slower runtimes with -optc-O3 and
> > -optc-ffast-math than without. Individually or in tandem. Odd. This is
> > ghc 6.4.1 and gcc 4.0.3 on a (Banias) Pentium M.
> 
> More architecture benchmarking:
> 
> On a powerbook G4, Joel Koerwer's entry on http://haskell.org/hawiki/NbodyEntry
> runs faster than dons+chris.
> 
> And I edited it to make it smaller, but by hoisting 'size' and 'dt' I also made
> it run quite a bit faster.  It now takes 1.7x less time than dons+chris.
> 
> Don, could you check the speed on your architecture?

Yes! I was missing the -funbox-strict-fields, it makes a huge
difference.  Check the wiki page, these stuarrays are the fastest yet.

Cheers,
  Don