[Cialug] Opteron and 64 bit architecture question

[Dave J. Hala Jr.]

Anyone running Dual Opteron's with Redhat enterprise 3?

On Tue, 2005-04-26 at 16:21, Aaron Porter wrote:
> On 4/26/05, Nathan C. Smith <smith@ipmvs.com> wrote:
> > My question is, if you run a 32 bit program on a 64 bit machine
> > (particularly AMD), does it have to recreate this memory access kludge in
> > the "emulation mode", or is this one of the ways it can give a little boost
> > to a 32 bit system running on a 64 bit architecture.
> 
> The "kludge" was for the OS to access more than 4gb, your applications
> were generally still limited to under 4.
> 
> > If I buy 64 bit machines now, and run 32 bit Oss on them, I will be
> > future-proofed to some degree, but will I get any benefit for the 32 bit OS
> > today?
> 
> Yes, but mainly from the memory hardware. AMD's HyperTransport kicks
> the pants off Intel's stuff.
> 
> > Anyone with an Opteron happy with it in 64 or 32 bit "mode"?  I have an
> > Athlon 64 Machine at work running Fedora Core 3 64.  It is a fast machine,
> > but I can't say that is is significantly faster than other machines,
> > subjectively, it actually "felt" faster running 32 bit FC3.
> 
> I've got ~150 dual cpu opterons running Debian Sarge i386 with a
> home-brew amd64 kernel. The vast majority of our apps are 32bit
> binaries, and the developers are months away from starting the
> (trivial) process of recompiling. We've seen anything from a 30-80%
> speed increase in run time (Opteron 246 @ 2ghz vs Xeon @ 2.2ghz) on
> the same binarires simply because of the faster memory bus. Night and
> day for most of our stuff.
> 
> We've also got Debian Sid amd64 running on a few of our larger boxes
> and desktops, and it's  been rock solid. Nothing more satisfying than
> watching a $10k amd64/debian box spank a $50k sun box.
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Dave J. Hala Jr. <dave@osis.us>
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