High MSU consumption with SYSVUSER

Products

• SYSVIEW Performance Management

Issue/Introduction

We are experiencing high CPU usage in the VTAM SYSVUSER component.    It has been running for several days and is continuously consuming CPU.   We had something similar in the 16.0 release but since IBM is charging the customer for MSU usage now, we'd like to better understand what is causing the usage.  

Environment

SYSVIEW 17.0 but could be any release

Cause

The customer noted that they had users using 4 second auto-update, who were not signing off at the end of their shifts.    

Resolution

This particular customer will need to internally manage the sessions, or set policies in place to have their users log off at the end of the shift.   

Some other tips for combating high CPU:

1. Reduce the update rate of CSYSDATA:   For this customer the new data is only being published every minute, however is reprocessing all the data every 2 seconds. After they are on the CSYSDATA screen, calling UPDATE 60 from the SYSVIEW command line will reduce the update rate to once every 60 seconds to reduce CPU without losing the usefulness of the data.

2. Limit the amount of data processed by CSYSDATA:   Instead of just calling CSYSDATA, they should call CSYSDATA LIMIT 100. This will limit the amount of rows being processed from ~1400 (as seen in the capture) to only displaying 100 (or they can replace 100 with a number that better suites their need, the smaller it is, the less CPU will be used).

Both of these options will reduce their CPU usage; however, implementing both will see a significant savings in CPU.

 

 

Additional Information

For assistance from Broadcom Support on high CPU issues, the following documentation should be provided:

1. General information on anything that may have changed recently to cause the high CPU
2. Note if the CPU is remaining consistently high, or does it have periods where it goes down
3. Complete SYSVIEW log
4. Complete SYSVUSER log 
5. Output from running command "CAPTURE DIAG0000" created during the period of high CPU.   This output should be tersed and transmitted in binary.
6. Console dump created by the following actions DURING the time of high CPU:  

                DUMP COMM=(dumpname)

                  Reply to the WTOR:

                  R xx,JOBNAME=(SYSVIEW,SYSVUSER),SDATA=(ALLNUC,PSA,CSA,SQA,LSQA,LPA,TRT,RGN,SUM,GRSQ),END