If you are running AIX on a PureApplication W3700 POWER8 system, you should pay attention to this APAR: IT14338: PureApplication System: Some AIX virtual machines have 8 SMT threads and others have 4 SMT threads per processor setting

The implications of this are that virtual machines that have been rebooted do not preserve their SMT8 setting and revert to SMT4. The fix for this issue is contained in the IBM AIX OS image beginning with PureApplication 2.2.1.0, but for any virtual machines deployed at earlier levels you need to take manual action to ensure the SMT8 setting is preserved.

You can preserve the SMT8 setting on your existing LPARs by following the instructions in this dwAnswers post: Why is SMT (simultaneous multi-thread) value set to 4 on my AIX virtual machine after VM reboot on PureApplication System W3700?