HP-UX Virtual Partitions Administrator Guide (includes A.05.08) (5900-1312, March 2011)

◦ keira1# vparmodify -p keira2 -a cpu::2
keira1# vparmodify -p keira2 -d cpu::1
◦ keira1# vparmodify -p keira2 -a mem::1024
keira1# vparmodify -p keira2 -d mem::512
• In the same command, you cannot make changes to both memory and CPU. For example,
the following are illegal:
◦ keira1# vparmodify -p keira2 -a cpu::2 -a mem::1024
CPU: Deleting CPUs Summary
• The current boot processor can not be deleted from a virtual partition. (Use vparstatus -v
to determine the current boot processor.) If you wish to delete a specific CPU that is being
used as a boot processor by a booted virtual partition, you will need to shutdown the virtual
partition and then delete the desired CPU.
CPU: vparstatus
• When a virtual partition is down, the CPUs assigned to that partition are reserved to that
partition and cannot be used for other partitions. For example, vparstatus does not show
any CPU assigned as the boot processor. The boot processor is not assigned until the virtual
partition is actually booted.
• If a virtual partition is down and assigned only one CPU, a CPU will be reserved by the vPars
Monitor, making it unavailable. The specific CPU reserved is not determined until boot time.
As a result, while the virtual partition is down, vparstatus -A, which shows available
resources, will show all the possible paths of unassigned CPUs but the count of available CPUs
will be one less. The count reflects the actual number of available CPUs because one CPU is
reserved for the down virtual partition.
CPU: Counts Summary
• At all times, the rule of min<=total<=max is enforced.
• When adding by CLP, the total count changes whether the partition is up or down.
• When adding by hardware path, the total count changes only when the partition is up. The
total does not change if the specified CPU is already assigned to the partition.
• When adding by hardware path and the partition is down, you cannot have the number of
CPUs added by hardware path exceed the current total value.
CPU: Dual-Core Processors
With the PA-8800s and other dual-core processors, there are two CPUs per socket. (On a cell
board with four sockets, this allows 8 CPUs per cell board.) The CPUs that share the socket are
called sibling CPUs.
Splitting sibling CPUs across virtual partitions refers to assigning one sibling CPU to one partition
and assigning the other sibling CPU to a different virtual partition. No noticeable performance
degradation has been seen when splitting sibling CPUs. Due to items such as the larger L2 cache
size, there actually can be a small performance boost if the siblings are split such that one of the
virtual partitions has no workload. If you require consistently predictable performance, configure
the virtual partitions consistently; in other words, decide whether to split siblings or keep them
together, and maintain that policy across all virtual partitions.
196 CPU, Memory, and I/O Resources (A.05.xx)