Investigating class 2 CPU times

Class 2 CPU times indicate the amount of time consumed in Db2 on the central processor during the accounting interval. It does not include application time.

To investigate high class 2 CPU times, complete the following investigations:

• Check whether unnecessary trace options are enabled.
  Excessive performance tracing can cause increased class 2 CPU times.
• Check the SQL statement count, the getpage count, and the buffer update count on the IBM® OMEGAMON® for Db2 Performance Expert on z/OS® accounting report.
  If the profile of the SQL statements has changed significantly, review the application. If the getpage counts or the buffer update counts change significantly, check for changes to the access path and significant increases in the number of rows in the tables that are accessed.
• Check for the access paths problems with the SQL statements in your application.
• Use the statistics report to check buffer pool activity, including the buffer pool thresholds. If buffer pool activity has increased, ensure that your buffer pools are properly tuned.
• Check the counts in the locking section of the IBM OMEGAMON for Db2 Performance Expert on z/OS accounting report. For a more detailed analysis, use the deadlock or timeout traces from statistics trace class 3 and the lock suspension report or trace.
  Latch contention is often a cause of high class 2 CPU times.