Determining Sample Intervals

The sample interval configured with rcapadm is the shortest amount of time rcapd waits between sampling a workload's usage and enforcing the cap if it is exceeded. If you reduce this interval, rcapd will, under most conditions, enforce caps more frequently, possibly resulting in increased I/O due to paging. However, a shorter sample interval can also lessen the impact that a sudden increase in a particular workload's physical memory usage might have on other workloads. The window between samplings, in which the workload can consume memory unhindered and possibly take memory from other capped workloads, is narrowed.

If the sample interval specified to rcapstat is shorter than the interval specified to rcapd with rcapadm, the output for some intervals can be zero. This situation occurs because rcapd does not update statistics more frequently than the interval specified with rcapadm. The interval specified with rcapadm is independent of the sampling interval used by rcapstat.