OT: Is the AMD Phenom processor upwards compabible with the Opteron

[Jonathan Ryshpan]

Thanks for your info, but your message leaves open exactly the two
questions that I was asking:

On Wed, 2009-08-26 at 12:15 -0700, Rick Stevens wrote:
> Jonathan Ryshpan wrote:
> > Configuring the kernel I came across a choice between generic-x86_64
> > processors, and the Opteron/Athlon/Hammer/K8 processors.  My system has
> > a 4-core Phenom processor.  Questions:
> > 
> >      1. Is the Phenom compatible with the Opteron/etc?  I.e. if I
> >         configure for the Opteron, will my kernel be reliable?  (This is
> >         not as easy to find out as I thought.)
> 
> To my knowledge, yes.  It's certainly compatible with the Athlon.  I run
> a Phenom quad-core as well, but I just use the off-the-shelf x86_64
> kernel.  Works fine.

I run the same kernel myself, built for the generic-x86_64 CPU.  The
question is are there enhancements for the Athlon above the generic,
which are not compatible with the Phenom.  I think not, but I haven't
been able to get any firm info yet.

> >      2. How much of a performance advantage is there to configuring for
> >         the Opteron as against the generic?
> 
> I don't know that you'd notice any significant difference with a normal
> work load.  If you were doing heavy I/O or number crunching, then you
> might see some difference, but not enough to really bother making a
> custom kernel.

Again, I suspect you're right about both things.  I have to build
another kernel to chenge the preemption rule from VOLUNTARY_PREEMPT to
PREEMPT, so this looked like a natural change to add (if it works).

Thanks - jon