The Inspect Address Space CPU Use workspace

The results of the inspection are displayed in the Inspect Address Space CPU Use workspace. The workspace contains three views: Sampling Statistics, Agent Messages, and Inspect Data.

The Sampling Statistics table view shows the number of samples requested, the sampling interval in milliseconds, the number of samples collected, and the number of samples used. Typically, the number of samples collected is the same as the number requested. However, if the job being inspected ends before the Inspect agent has finished collecting data, the number of samples collected is the number collected up to the point where Inspect detected that the target job had ended.

The number of samples used is the number of times that the Inspect agent saw CPU activity in the target address space and gives you some indication as to the statistical accuracy of the resultant inspect data. The number of samples used value does not represent the number of rows of Inspect data.

The Agent Messages view displays any error or informational messages returned by the Inspect agent. These messages help to explain the resultant data (or lack thereof) that you see in the other views. For example, if no CPU activity was seen by Inspect in the address space being inspected, the agent returns a message indicating that; the number of samples used column in the Sampling Statistics view would be zero; and no data would be displayed in the Inspect Data view.

The Inspect Data view contains the output from the inspection process. The Inspect agent returns data only for elements for which it saw CPU activity. The data is ordered in descending CPU activity order with the following hierarchy:

  • Task control block (TCB)
  •    Load module within TCB
  •       Control sector (CSECT) within load module
  •          Block of code within CSECT
  • Task control block

For each TCB for which it sees processor activity, Inspect attempts to determine the executing load modules consuming the processor time (CPU). For each load module, Inspect then attempts to map the CSECT structure of the load module and assign the load module processor time to the appropriate CSECTs. This allows you to determine which load modules and CSECTs within the load module are consuming processor time.

Inspect maps the CSECT structure for each load module (with processor activity) by scanning the target address space for load libraries and attempting to read in the load module from each library in turn. It also scans SYS1.LINKLIB, SYS1.NUCLEUS and SYS1.LPALIB for load modules. If Inspect cannot locate the load module, the CSECT name is unknown and the entire load module is considered to be one large CSECT.

Inspect then further breaks down the CPU time attributed to each CSECT into blocks of code, the size of which is calculated by Inspect once the data collection process has completed. In order to prevent Inspect from flooding the client workspace with rows of data, the Inspect agent attempts to calculate a granularity (block) size that will limit the number of rows of data returned to about 100, but where possible the Inspect agent will use a granularity size of 16 bytes (0X00000010). The granularity size used is displayed in the Agent Messages view of the Inspect CPU Use workspace. The granular data is shown in the rightmost two columns of the Inspect Data view. Again, these are displayed in descending processor use order with the most active blocks of code within each CSECT being at the top of the display rows for each CSECT.

Tip: Before you examine the Inspect data, review the Samples Used field in the Sampling Statistics view. This field indicates the statistical validity of the sampled data. A low number of samples indicates that the Inspect data may not give a truly representative view of where the code in the target address space is spending its time. Also review any messages in the Agent Messages view that may indicate that the data might be incomplete, or explain why there is no data. You can find descriptions of the Inspect messages in the online help.

For descriptions of the information in the columns of these tables, see Inspect Address Space CPU Use attributes.