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Re: st: Macs and 64-bit Memory Addressing


From   Michael Ingre <Michael.Ingre@ipm.ki.se>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Macs and 64-bit Memory Addressing
Date   Tue, 04 Nov 2003 16:20:42 +0100

cnguyen@stata.com <cnguyen@stata.com>:

> Anyway, let's remember that Apple kept the G5 under wraps for a while and that
> Metrowerks (who have been at the compiler game a lot longer than Apple and
> saved Apple's bacon when the first PowerPC was released) will add G5 support
> to their compiler eventually.  And when they do, I expect the same sort of
> minimal speed gains I'm seeing now with gcc 3.3 because the sort of
> optimizations they perform are not of great benefit to Stata.
 
I guess that you have made a good choice of sticking with Metrowerks. And
probably, G5 support will be added to code warrior long before I have the
means to get my own G5 from apple.

However, what you're suggesting is a bit puzzling to me. I always thought
that there would be a huge boost in performance (several times faster rather
that a few percent) when calculating 64 bit data types in native 64-bit code
compared to 32-bit code. And this would (presumably) greatly increase speed
in programs like Stata that rely heavily on calculations with 64-bit data
types. 

Apple suggest that calculations with 64-bit integer and floats cold be done
in one clock cycle with the G5. But, they don't tell how many cycles a G4
would need for the same operation.

Micke

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