Oracle database performance on P7 servers with SMT4
We are troubleshooting performance issues for an application.
Environment is as follows :
AIX 7.1 hosted on P7 LPAR
SMT=4
Entitled Capacity = 16
Virtual Processors = 16
Oracle database : 11.2.0.3 , 2 node RAC.
We have noticed unbalanced CPU utilisation.
Under regular load, NMON output shows utilisation on every 4th CPU is (CPU 0,4,8,12..) peaks to 50%. The other CPU's are almost 0%.
Under more-than-regular load, NMON output shows utilisation on every 4th + 1 CPU is (CPU 0,1,4,5,8,9,12,13..) peaks to 50%. The other CPU's are almost 0%.
Is this the default behaviour on P7 machines with SMT4 enabled ?
Whenever we run a batchjob which executes in 40 - 60 sessions, on the database end, we have noticed CPU waits (in OEM performance page). Is this related to the behaviour seen in NMON outputs ?