Benchmarks: AMD64 vs i386 on Dual 246 Opteron

David O'Brien obrien at
Tue Aug 2 17:49:37 GMT 2005

On Fri, Jul 29, 2005 at 02:06:09AM -0700, ray at wrote:
> In going over my notes, the only thing I
> can see that might have been a mistake was if I left out 'options SMP'
> from the AMD64 kernel config file.  But I seem to recall you do not
> have to include that on AMD64 like you do with i386 - can anyone
> confirm this?

Totally false!  A kernel w/o 'options SMP' is a UP kernel and only uses a
single CPU.  I suspect is what you are mis-remembering is that an AMD64
SMP kernel will boot and work just fine on a UP AMD64 machine.  (which
hasn't been the case on i386 in the past)

-- David  (obrien at

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