istributed performance problem when using WLM GOAL mode when the system is completely utilized.
Problem
If your system is running at 100% CPU utilization and you are using WLM GOAL mode, the performance of your distributed jobs is likely to decrease.
Solution
Symptoms:
If you are running DB2 Version 4 or above and you are also using WLM GOAL mode, when the system reaches 100% CPU utilization, you might notice that your distributed jobs run more slowly than expected.
Cause:
When your system load is near 100% CPU utilization and your WLM environment is running in GOAL mode, and your distributed requests are experiencing slow performance, you should check to see if classification rules have been defined for SUBSYS=DDF work, that is, DDF work enclaves. If there are no classification rules, then by definition of GOAL mode, the SUBSYS=DDF work has no goal, which means that WLM will assign the SYSOTHER service class to any distributed work enclave. An enclave (TCB or SRB) running under SYSOTHER only gets CPU when it needs it if and only if there is available CPU capacity.
Solution:
To quickly remedy this situation while one is determining what SUBSYS=DDF work will be assigned to which service class, specify a default service class in the classification rules for the SUBSYS=DDF definition panel so that the DDF work enclaves now have a goal.
Historical Number
APAR: II10488
P.S. Please pass my address to anyone interested in DB2 HOTLINE - thank you.
With kind regards
Michael Dewert, Software Group
DB2 Information Management Software
