Automatic System Tuning

Tuning is a way of adjusting the performance of a system. For basic tuning, automatic system tuning is a useful method to maintain good performance. This can be done by setting the system value QPFRADJ to indicate that system tuning adjustments are performed at IPL time or dynamically while the system is running.

Do not use the QPFRADJ value and the SETOBJACC command at the same time for a shared pool. QPFRADJ removes storage from a shared pool that has no paging activity. If the SETOBJACC command is used to preload an object into the same pool, it may lose some of its storage. The SETOBJACC command is used to cause no page faulting to occur in the pool, and QPFRADJ would consider that pool a prime candidate for removing storage.

In some cases, QPFRADJ at IPL should not be used because IPL tuning can undo acceptable performance that is achieved by dynamic tuning or manual tuning done during normal system operation. In an environment with the same number of active jobs and no new applications, QPFRADJ is set to 0 after it has been used to obtain optimal paging rates across the system.