fons at kokkinizita.net
Mon May 5 22:24:28 UTC 2008
On Tue, May 06, 2008 at 12:10:38AM +0200, Jens M Andreasen wrote:
> On Mon, 2008-05-05 at 23:32 +0200, Jens M Andreasen wrote:
> > > clock: 4020 ms (_Complex)
> > > clock: 1550 ms (cvec_t)
> > > clock: 70000 ms (original float array[N])
> Wait a second ... It's a trick! :-D
> The compiler splits the iterations up in smaller parts that fits in the
> cache and runs them in succesion.
I've know one what that even more clever. It just noticed I didn't use
the result, and skipped the whole loop.
After each iteration, call an empty function, separately compiled,
that takes all three vectors as arguments (and _not_ as const *
of course). No more tricks. The overhead is peanuts compared
to the calculation.
Laboratorio di Acustica ed Elettroacustica
Lascia la spina, cogli la rosa.
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