Micro-Partitioning

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Micro-Partitioning is a form of Logical partitioning which was introduced by IBM on systems using the POWER5 processor, and are also referred to as a shared processor partition, and only differs from a dedicated processor partition in the way CPU utilization are configured and managed by the POWER Hypervisor (PHYP) firmware. All IBM POWER5 and POWER6 systems are partitioned and will run "on top" of the PHYP.

The POWER Hypervisor controls time slicing, management of all hardware interrupts, dynamic movement of resources across multiple operating systems, and dispatching of logical partition workloads.

When a shared processor partition are activated by the PHYP, the LPAR are guaranteed by the PHYP a certain processing capacity, if needed, and number of virtual processors, based on configuration and current availability. The processing capacity are drawn from a pool of shared processor resources.

The minimum processing capacity per processor are 1/10 of a physical processor core, with a further granularity of 1/100, and the PHYP use a 10 ms time slicing dispatch window for scheduling all shared processor partitions virtual processor queues to the PHYP physical processor core queues. A shared processor partition can be either capped or uncapped. A capped partition can never exceed the currently configured processing capacity, whereas an uncapped partition can exceed the currently configured processing capacity up to 100% of the number of the currently configured virtual processors.

If the shared processor partition are DLPAR capable, the number of virtual processors and processing capacity can be altered dynamically for the partition.

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