5.56 NUMCPU (Number of emulated CPUs)
5.56.1 Function
NUMCPU specifies the number of emulated processor engines which will be configured online at startup
time. The combination of NUMCPU and MAXCPU controls the behaviour of how many CPU engines will
be configured online upon startup and how many can be configured online later.
NUMCPU cannot exceed the value of MAXCPU. If NUMCPU is less than MAXCPU then the remaining
engines can be configured online later. The default NUMCPU value is 1. All processors are CP engines
unless otherwise specified by the ENGINES system parameter.
Multiprocessor emulation works best if your host system actually has more than one physical CPU, but
you can still emulate multiple CPUs nevertheless even on a uniprocessor system (and you might even
achieve a small performance benefit when you do).
There is little point, however, in specifying NUMCPU greater than 1 unless your guest operating system
(running under Hercules) is actually able to support multiple CPUs. If you do not actually need multipro-
cessor emulation, then setting MAX_CPU_ENGINES to 1 at compile time might even produce a slight
performance advantage too.
For detailed explanations on the interrelationship between NUMCPU, MAXCPU and ENGINES please
see “
5.56.2 Syntax
Descriptive
1 nn
Diagram
Êʬ¬¬ ¬¬¬§¬¬¬ 1 ¬¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬ÊÍ
nn
5.56.3 Parameter
nn
The number of emulated CPUs. NUMCPU must be less than or equal MAXCPU. If
NUMCPU is larger than MAXCPU then an error message is issued, if it is less than
MAXCPU then the remaining engines can be configured online later. The default
for NUMCPU
is 1.
