Processor use and memory use controls

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Processor use controls and memory use controls allow you to allocate processor and memory resources for the global environment.

You can use share-based allocation or percentage-based allocation for processor and memory resources.
Note: Both share-based controls and percentage-based controls can be specified. In the event of conflict, the percentage-based controls take precedence.
Share-based allocation

The percentage of CPU or memory to allocate to the WPAR is determined by dividing the number of shares by the total number of shares allocated to all active WPARs. The number of shares represents how much of a particular resource a WPAR receives relative to the other WPARs.

For example, if there are three active WPARs (A, B, and C) with shares for a particular resource of 15, 10, and 5, allocation targets would be the following:
  • WPAR A, 15/30 or 50%
  • WPAR B, 10/30 or 33%
  • WPAR C, 5/30 or 17%
Allocation targets adjust with the number of active workload partitions. If partition A is inactive, then the allocation targets would be the following:
  • WPAR B, 10/15 or 66%
  • WPAR C, 5/15 or 33%

Share-based allocation is specified by using the shares_CPU option with the mkwpar command or the chwpar command.

Percentage-based allocation
The percentage of CPU or memory to allocate to the WPAR is determined by the following user-specified values:
min%
The minimum amount of a resource that should be made available to the WPAR. If the actual consumption is below this value, the WPAR will be given highest priority access to the resource. The possible values are 0 to 100, with a default value of 0.
soft%
The maximum amount of a resource that a WPAR can use when there is contention for that resource. If the WPAR's consumption exceeds this value, the WPAR will be given the lowest priority access to the resource. If there is no contention for the resource, the WPAR is allowed to consume as many resources as it requires. The possible values are .01 to 100, with a default value of 100.
hard%
The maximum amount of a resource that a WPAR can consume, even when there is no contention. If the class reaches this limit, it will not be allowed to consume any more of the resource until its consumption percentage falls below the limit. The possible values are .01 to 100, with a default value of 100.
Note: Using hard maximum limits can have a significant impact on system or application performance if not used appropriately. Because imposing hard limits can result in unused system resources, in most cases, soft maximum limits are more appropriate.