[Beowulf] Peformance penalty when using 128-bit reals on AMD64

Nifty Tom Mitchell niftyompi at niftyegg.com
Fri Jun 25 11:54:24 EDT 2010


On Fri, Jun 25, 2010 at 10:28:15AM -0400, Prentice Bisbal wrote:
> 
> Beowulfers,
> 
> One of my Fortran programmers had to increase the precision of his
> program so he switched from REAL*8 to REAL*16 which changes the size of
> his variables from 64 bits to 128 bits. The program now takes 32x longer
> to run.
> 

I am surprised that it works as support in things like
the math lib, log and trig functions could be missing.
Which compiler is he using?





-- 
	T o m  M i t c h e l l 
	Found me a new hat, now what?

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