CPU Configuration Guidelines for vPars

Figure 20. Interrupt assignments as viewed from the output of the intctl command.

4.3 Count Based CPU Migration

When the workload on vpolyc01 increases, one or more CPU’s can be added to process the

additional load. The following vparmodify example shows the syntax that should be used to add the

count based CPU’s.

vparmodify –p vpolyc01 –a cpu::2

As mentioned earlier, adding CPU’s does not change the interrupt assignment so all interrupts are still

assigned to the four original CPU’s. Now when the workload on vpolyc01 decreases, the extra CPU’s

can be deleted from the partition with the following command.

vparmodify –p vpolyc01 –d cpu::2

Since the only count based CPU’s in vpolyc01 were the two that we added to handle the increased

load, those are the CPU’s deleted from the partition by the vparmodify command. Another way to

looking at it, the other CPU’s in the partition are path based CPU’s and can’t be deleted with count

based semantics. As a result, no I/O interrupts are redistributed when count based CPU’s are added

or deleted from the partition.