Installing and Managing HP-UX Virtual Partitions (A.02.01)

Managing Virtual Partitions
CPU Allocation
Chapter 348
CPU Allocation
Bound and Unbound CPUs
With vPars, there are two types of CPUs: bound and unbound.
A bound CPU is a CPU that is assigned to and handles I/O interrupts
for a virtual partition. Every virtual partition must have at least one
bound CPU to handle its I/O interrupts.
CPUs that are not assigned to any virtual partition or that are assigned
to a virtual partition but do not handle its I/O interrupts are unbound
CPUs. Unbound CPUs are sometimes called floater CPUs.
All CPUs begin as not being assigned to any virtual partition, so all
CPUs begin as unbound CPUs. Using the vPars commands, you can
assign CPUs to virtual partitions as bound or unbound.
For more information on how to do this using the vPars commands, see
“Adding and Removing CPU Resources” on page 141.
CPU Migration
CPU migration refers to adding CPUs to and deleting CPUs from a
virtual partition. Dynamic CPU migration refers to migrating CPUs
while the target virtual partition is running.
You can migrate both bound and unbound CPUs, but because HP-UX
cannot dynamically migrate I/O interrupts, you can dynamically migrate
only unbound CPUs.
For more information on how to migrate bound and unbound CPUs, see
“Adding and Removing CPU Resources” on page 141.
Determining Whether to Use Bound or Unbound
CPUs
When the applications within the target virtual partitions are I/O
intensive, use bound CPUs because only bound CPUs can process I/O
interrupts; specifically, with I/O intensive applications there should be
more bound CPUs than unbound CPUs.