On Fri, Mar 16, 2001 at 01:39:59PM -0000, Breathnach, Proinnsias (Dublin) wrote:
> Which begs the question ...
> Is there such a thing as Assymetric Multi Processing, using multiple
> *different* processors on a box ...
> > -----Original Message-----
> >
> > Symmetric multi processing. Basically, using two or more identical
> > processors.
That's not what the symmetric in SMP means. It refers to the jobs performed
by the processors, not the processors themselves.
Classic example: The VAX-11/782 was a dual-processor VAX-11/780 but was
refered to by Digital as an Asymmetric MultiProcessing system. Refers
to VAX Hardware Handbook:
The VAX-11/782 Atatched Processor System is classified as a tightly
coupled, asymmetric multiprocessor system. It is based on the MA780
multiport memory subsystem [...]
In a tightly coupled system, the CPUs execute the same copy of the
operating system code and share the same data structures.
Asymmetric CPUs cannot execute the entire operating system code at
the same time. In this system, all kernel mode and interrupt code
is executed by the primary processor. The primary processor schedules
all work for the attached processor before scheduling itself.
(This beast was about 5' high, 2.5' deep and 10' long. Wouldn't fit
in my computer room at home, unfortunately... :-(
In SMP, the CPUs are capable of performing the same tasks, such as
receiving interrupts and running kernel code.
Later,
Kenn
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