[Haifux] Running 32 bit applications (Firefox?) on 64 bit machines

Orna Agmon Ben-Yehuda ladypine at gmail.com
Mon Aug 22 14:15:21 MSD 2011

On Mon, Aug 22, 2011 at 10:17 AM, Nadav Har'El <nyh at math.technion.ac.il>wrote:

> On Sun, Aug 21, 2011, Orna Agmon Ben-Yehuda wrote about "Re: [Haifux]
> Running 32 bit applications (Firefox?) on 64 bit machines":
> > I forgot to mention that sometimes, on really funny occasions, you get a
> > performance penalty from using the 64bit code. For example, when you take
> a
> > number close to 1 (1.00000001) to a power. You will get absolutely stuck
> > with the 64bit code.
> This is really bizarre...
> I wonder how x86 and x86-64 differ in that regard?
I found an explanation by Paul Murphy, saying the x86 implementation is very
optimized in assembly.

An ad-hoc solution we found was (when the accurate result was not required,
just an approximation) :
to cast the double to a float, perform the power operation, then cast back
to double. It solved the slowness, but I don't know what to do when I
actually need the accurate result.

> Nadav Har'El                        |          Monday, Aug 22 2011, 22 Av
> 5771
> nyh at math.technion.ac.il
> |-----------------------------------------
> Phone +972-523-790466, ICQ 13349191 |Unix is simple, but it takes a genius
> to
> http://nadav.harel.org.il           |understand its simplicity.

Orna Agmon Ben-Yehuda.
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