Setting up a Monitor Definition › Samples and Observations › Sampling Rules

Sampling Rules

When samples are created to reflect the activity of a TCB, there are certain rules which determine if the sample shows any noteworthy activity. These rules are as follows:

• If a TCB is actively using the CPU, a sample is always written for the TCB.
• If the TCB is waiting and is not the jobstep task (subtask) and the ECB that the TCB is waiting for cannot be related to anything that CA Mainframe Application Tuner reports (file activity, database activity, and so on), the sample is discarded. For instance, if a subtask is waiting for an ECB for an internal work queue that is only known to the application, the sample is discarded. If the ECB relates to file activity, the sample is considered noteworthy and is written to the monitor file.
• If the TCB is the jobstep TCB, all waiting activity is recorded with one exception. If the ECB or an ECB within an ECB list contains the termination ECB of a subtask, the waiting sample for the jobstep TCB is discarded. It is assumed by CA Mainframe Application Tuner that if a task waits for a subtask to be completed, it is performing the same functionality as a LINK but doing it with ATTACH instead.

Because of these rules, there can be large fluctuations in % Samples Active and % Samples Waiting. Without knowledge about the application and the address space type, the numbers might appear to be invalid in a multitasking and multi-CPU environment.