In previous versions of BIG-IP, the majority of the traffic was processed by the system kernel. Beginning in version 9.0, the Traffic Management Microkernel (TMM) processes traffic. This change causes UNIX command utilities, such as top and ps, to inaccurately report CPU utilization at approximately 80% utilization for single processor systems and 99% on dual processor systems.
For this reason, you should not use UNIX utilities to monitor CPU utilization. For an accurate depiction of TMM CPU utilization, click Performance from the Main tab of the BIG-IP Configuration utility.
For more information about TMM CPU utilization, refer to SOL3242: Overview of Traffic Management Microkernel (TMM) CPU and RAM usage.