Re: [Fwd: libfreevec benchmarks]
Στις Tuesday 09 September 2008 01:00:42 ο/η Rogério Brito έγραψε:
> This might explain my impression in a private mail to Charles Plessy
> that my iBook G3 was quite faster under Linux than under MacOS X.
> Apparently, MacOS X is *made* *for* altivec machines.
True, Altivec is quite extensively used in MacOS X, which is not sth I can say
for any core component of Linux, sadly. This was exactly the reason I started
libfreevec in the first place.
> This would be very welcome addition to glibc. Especially for the
> "weaker" chips that don't have any vectorial part.
These won't be accelerated though, only in the case that the original
algorithm was optimised as well,
> This part about not using altivec is interesting, since I would like to,
> say, be able to watch DVDs with my iBook and not have them drop so many
> frames. Decoding theora videos is also quite CPU intensive... :-(
Well, I can't really say how much faster decoding will be with faster libm
functions, but 3D definitely will be faster.
> > > just by choosing a different approximation method (Taylor
> > > approximation is pretty dumb if you ask me anyway).
>
> What are you using, BTW? CORDIC?
No, Pade approximations. CORDIC iirc, is also not that much faster than
Taylor. I have some relevant paper around but I can't seem to find it right
now, but I could look it up if you really like.
Anyway, the libm rewrites will be accompanied by a math paper full with proof
and benchmarks, so I guess you will see the method used :)
Regards
Konstantinos Margaritis
Codex
http://www.codex.gr
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