Uncapped Shared Processor Partitions - IBM p5 590 System Handbook

Uncapped partitions
An uncapped partition has the same definition of a capped partition, except that
the maximum limit of processing capacity limit is a soft limit. That means that an
uncapped partition may eventually receive more processor cycles than its
entitled capacity.
In the case it is using 100 percent of the entitled capacity, and there are idle
processors in the shared processor pool, the POWER Hypervisor has the ability
to dispatch virtual processors from the uncapped partitions to use the extra
capacity.
In the example we used for the capped partition, if we change the partition from
capped to uncapped, a possible chart for the capacity utilization is the one shown
in Figure 3-3. It still has the equivalent of 9.5 physical processors as its
entitlement, but it an use more resources if required and available.
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Figure 3-3 Uncapped shared processor partitions
The number of virtual processors on an uncapped partition defines the largest
capacity it can use from the shared processor pool. By making the number of
virtual processors too small, you may limit the processing capacity of an
uncapped partition. A logical partition in the shared processing pool will have at
least as many virtual processors as its assigned processing capacity. If you have
a partition with 0.50 processing units and 1 virtual processor, the partition cannot
exceed 1.00 processing units because it can only run one job at a time, which
cannot exceed 1.00 processing units. However, if the same partition with 0.50
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Chapter 3. POWER5 virtualization capabilities
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