Chapter 3. Virtualization
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Draft Document for Review October 14, 2014 10:19 am
5137ch03.fm
Micro-Partitioning
When you use the Micro-Partitioning technology, you can allocate fractions of processors to a
logical partition. This technology was introduced with POWER5 processor-based systems. A
logical partition using fractions of processors is also known as a
shared processor partition
or
micropartition
. Micropartitions run over a set of processors that are called a
shared processor
pool
, and virtual processors are used to let the operating system manage the fractions of
processing power that are assigned to the logical partition. From an operating system
perspective, a virtual processor cannot be distinguished from a physical processor, unless the
operating system is enhanced to determine the difference. Physical processors are
abstracted into virtual processors that are available to partitions. The meaning of the term
physical
processor
in this section is a
processor core
.
When defining a shared processor partition, several options must be defined:
The minimum, wanted, and maximum processing units
Processing units are defined as processing power, or the fraction of time that the partition
is dispatched on physical processors. Processing units define the capacity entitlement of
the partition.
The shared processor pool
Select a pool from the list with the names of each configured shared processor pool. This
list also shows, in parentheses, the pool ID of each configured shared processor pool. If
the name of the wanted shared processor pool is not available here, you must first
configure the shared processor pool by using the shared processor pool Management
window. Shared processor partitions use the default shared processor pool, called
DefaultPool by default. For more information about multiple shared processor pools, see
3.4.3, “Multiple shared processor pools” on page 122.
Whether the partition can access extra processing power to “fill up” its virtual processors
above its capacity entitlement (you select either to cap or uncap your partition).
If spare processing power is available in the shared processor pool or other partitions are
not using their entitlement, an uncapped partition can use additional processing units if its
entitlement is not enough to satisfy its application processing demand.
The weight (preference) if there is an uncapped partition.
The minimum, wanted, and maximum number of virtual processors.
The POWER Hypervisor calculates partition processing power based on minimum, wanted,
and maximum values, processing mode, and the requirements of other active partitions. The
actual entitlement is never smaller than the processing unit’s wanted value, but can exceed
that value if it is an uncapped partition and up to the number of virtual processors that are
allocated.
On the POWER8 processors, a partition can be defined with a processor capacity as small as
0.05
processing units. This number represents 0.05 of a physical core. Each physical core
can be shared by up to 20 shared processor partitions, and the partition’s entitlement can be
incremented fractionally by as little as 0.01 of the processor. The shared processor partitions
are dispatched and time-sliced on the physical processors under control of the POWER
Hypervisor. The shared processor partitions are created and managed by the HMC.
The Power E870 supports up to 80 cores in a single system. Here are the maximum
numbers:
80 dedicated partitions
1024 micropartitions
