On Tue, Jun 11, 2002 at 08:16:38PM +0930, Brett Lymn wrote:
> On Tue, Jun 11, 2002 at 11:23:23AM +0100, David Laight wrote:
> > 
> > There is no real reason for it to lock up. It actually (probably)
> > tests your locking code slightly more thoroughly.
> >
> 
> Ummm actually there are lots of reasons for it to lock up :-)  I speak
> from experience here - we had a sun machine that someone accidentally
> put processor modules of differing clock speeds in.  Theoretically,
> the mbus (this was a SS10) is supposed to handle this.  In reality,
> the machine did a hard hang after a few hours of operation and we had
> to turn the power off and on again to get it's attention.

The Intel SMP specification allows for processors with different speeds.

http://www.intel.com/design/pro/datashts/242016.htm

"B.8 Supporting Unequal Processors
Some MP operating systems that exist today do not support processors of
different types, speeds, or capabilities. However, as processor lifetimes 
increase and new generations of processors arrive, the potential for
dissimilarity among processors increases. The MP specification addresses this
potential by providing an MP configuration table to help the operating system
configure itself.  Operating system writers should factor in processor
variations, such as processor type, family, model, and features, to arrive at
a configuration that maximizes overall system performance. At a minimum, the
MP operating system should remain operational and should support the common
features of unequal processors."


-Andrew