5.2.2. Sharing Mode cap

If the sharing mode cap has been configured for an LPAR, the LPAR can receive at most its guaranteed share (desired_proc_units) of processing units. Additional CPU time is not assigned to such an LPAR. Guaranteed CPU shares that are not used by the LPAR are returned to the shared processor pool and can be used by other LPARs with sharing mode uncap.

Figure 5.7 shows the processor utilization of a capped LPAR. The entitlement is 0.6 (yellow line) and one virtual processor has been configured (red line). If the LPAR does not use up its guaranteed entitlement, or only partially, then the unused portion is given to other LPARs (ceded capacity – light yellow). These shares go back to the hypervisor (or the shared processor pool) and are distributed to other LPARs. The portion of the guaranteed entitlement used by the LPAR is shown in green in the graph. The sum of the used guaranteed portion (green) and the unused portion (light yellow) is equal to the guaranteed entitlement, here 0.6. The graphic clearly shows that the LPAR does not receive any processor shares beyond its guaranteed entitlement.

Processor utilization of an LPAR with sharing mode cap
Figure 5.7: Processor utilization of an LPAR with sharing mode cap