DB CPU and resmgr.cpu.quantum event in top 10 foreground events

after migrating a database from 11.2.0.4 to 12.1.0.2 we encountered some performance issues.

The AWR report is showing this:

Top 10 Foreground Events by Total Wait Time:

Event                      Wait          Total Wait Time (sec)              
   Wait Avg(ms)               % DB time        Wait Class
DB CPU                                   201.1K                             
                                           75.5
resmgr.cpu.quantum 930,919     33.7K                                       
36.22                           12.7                  Scheduler
 

I think to explain DB CPU would not be easy, but we have found by investigating other java program on the oracle server (Redhat ) that the ulimit was set to a lower value (1024). I'm not sure if this has to do with DB CPU time.  

Furthermore I checked the parameter resource_manager_plan and found following:

in the new instance (12.1.2.1 RAC) the parameter is set to MIXED_WORKLOAD_PLAN. Here we have performance problems in the old instance (11.2.0.4 RAC) the parameter is set to null. (Everything work as expected)
Maybe this could explain the 12.7% DB time for resmgr.cpu.quantum  

Has anyone encountered problem using this parameter set to MIXED_WORKLOAD_PLAN?   Best regards
Ahmed  



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