[Haskell-cafe] Known Unknowns

Donald Bruce Stewart dons at cse.unsw.edu.au
Thu Jan 26 07:11:27 EST 2006

> Donald Bruce Stewart wrote:
> > haskell:
> >> There is a new combined benchmark, "partial sums" that subsumes several earlier
> >> benchmarks and runs 9 different numerical calculations:
> >>
> >> http://haskell.org/hawiki/PartialSumsEntry
> > 
> > Ah! I had an entry too. I've posted it on the wiki.  I was careful to
> > watch that all loops are compiled into nice unboxed ones in the Core. It
> > seems to run a little bit faster than your more abstracted code.
> > 
> > Timings on the page.
> > 
> > Also, -fasm seems to only be a benefit on the Mac, as you've pointed out
> > previously. Maybe you could check the times on the Mac too?
> > 
> > -- Don
> > 
> Yeah. I had not tried all the compiler options. Using -fasm is slower on this
> for me as well.  I suspect that since your code will beat the entries that have
> been posted so far, so I thin you should submit it.

ok, I'll submit it.
> Also, could you explain how to check the Core (un)boxing in a note on the (new?)
> wiki?  I would be interested in learning that trick.

Ah, i just do: ghc A.hs -O2 -ddump-simpl | less
and then read the Core, keeping an eye on the functions I'm interested
in, and checking they're compiling to the kind of loops I'd write by
hand. This is particularly useful for the kinds of tight numeric loops
used in some of the shootout entries.


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