Re: Q: Fast computation of parity

From: Tom St Denis (tomstdenis_at_iahu.ca)
Date: 12/31/03 

Date: Wed, 31 Dec 2003 18:15:14 GMT

"Michael J. Fromberger" <Michael.J.Fromberger@Clothing.Dartmouth.EDU> wrote
in message
news:Michael.J.Fromberger-81B301.12263031122003@merrimack.dartmouth.edu...
> Done. I had to increase the number of tests again to get the resolution
> high enough to see a difference on the P3.
>
> With:
> gcc -ansi -Wall -O3 -fomit-frame-pointer -funroll-loops -o pars pars2.c
>
> # On G4:
> % ./pars
> Lookup: 2
> XOR: 1
>
> # On PIII:
> % ./pars
> Lookup: 450000
> XOR: 460000

That's totally odd. Cuz on the x86 the dependency chain basically breaks
any form of parallelism. So I'd think the lookup would be faster...

Tom

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