The entPhysicalIndex of the physical entity for which
the statistics in this entry are maintained. The physical
entity can be a CPU chip, a group of CPUs, a CPU card etc.
The exact type of this entity is described by its
entPhysicalVendorType value. If the CPU statistics in this
entry correspond to more than one physical entity (or to no
physical entity), or if the entPhysicalTable is not supported
on the SNMP agent, the value of this object must be zero.