Db2 CPU Usage

Db2 uses MVS cross memory services extensively in processing application requests. As a result, the majority of CPU time consumed in processing thread activity is attributed by MVS SRM to the thread-originating (user's) address space, not to one of the Db2 system address spaces (SSAS, DBAS, IRLM).

OMEGAMON for Db2 PE provides CPU use information for threads within Db2. In all cases in which CPU use is reported, the CPU rate is expressed in terms of 1-100%, regardless of the number of CPUs online in the processor complex.

The discussion below is designed to help you interpret and make use of the information provided by OMEGAMON for Db2 PE regarding CPU usage.

Db2 exploits MVS CPU timing services introduced in MVS/XA SP2.2 and MVS/ESA.

OMEGAMON for Db2 PE also exploits the new CPU timing services as it monitors a Db2 subsystem. To accurately interpret CPU utilization data reported by OMEGAMON for Db2 PE, first consider the type of Db2 attachment that is in use. That is, did the threads in question originate from a CICS attachment or from another type of attachment (IMS, TSO, and so on)?