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Re: AMD64 64bit vs 32bit speed increase



On Fri, 2004-02-13 at 17:32, Chris Cheney wrote:
> On Fri, Feb 13, 2004 at 06:00:38PM -0500, C. Scott Ananian wrote:
> > On Fri, 13 Feb 2004, Chris Cheney wrote:
> > 
> > > I just did a simple speed test with oggenc 32bit vs 64bit under a 64bit
> > > kernel to see what kind of speed increase we could see... I picked ogg
> > > since I maintain it and its typically cpu bound.
> > 
> > what compiler options were used/what optimization levels?
> >  --scott
> 
> Default optimizations I just rebuilt the debian source without the extra
> plugins that depended on KDE/NAS/XFree86. I am not sure what the source
> itself does or if it has been optimized for amd64 yet. The Debian
> packaging itself certainly doesn't do anything special.

Which is as it should be: What matters is what i386's compile defaults
are going to be, not the handful of per-x86-CPU-optimized packages (ala,
kernel-image-CPU).

Sure, the 32-bit + SSE version may be faster than the 64-bit + SSE
version...   but if Debian i386 has only the 386^H^H486 version (no SIMD
optimizations, etc.), then the AMD64 version is gonna win on all but
cache-intensive, non-FPU-bound apps. Admittedly, this probably includes
a good many Unix system utilities, but since I'm an amd64 desktop user,
I'm highly interested FPU optimization.

-s

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