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:In a multi processor environment, when is the second CPU used?
:Where do I find information on the advantages?
:We may want to buy this type of machine once we understand the
:benefits.
OpenVMS SMP systems with up to twelve processors are not unusual.
The OpenVMS scheduler automatically and transparently handles
process scheduling on symmetric multiprocessor (SMP) systems:
The process scheduler will schedule any and all computable
processes on the next available processor(s), up to the number
of processors available on the system.
The basic "granularity" of the scheduler is the process, or -- on
those OpenVMS versions and applications that support it -- the
process thread. The scheduler will schedule a single computable
process or a single computable process thread on a each available
processor, until it runs out of computable processes or threads,
or out of processors.
Multiple processes environments, and particularly environments with
mixed user and batch/server loading, can form an ideal workload for
an SMP system.
A single application does not generally take advantage of the full
capabilities of an SMP system, unless the application is explicitly
coded to do so via standard parallel processing techniques such as
DECthreads (on those OpenVMS releases that support threading), or
is explicitly coded to operate via the creation of a set of seperate
(but cooperating) processes.
Note that one can run multiple copies of most applications entirely
in parallel, and each of these parallel processes can take advantage
of one of the processors in an SMP system.
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