8.4.1 WLM capabilities
WLM is an integral part of the AIX kernel, always installed but not enabled by default.
WLM is a feature of AIX 5.1 ML3 or AIX 5.2. There is a restricted form in AIX 4.3.3 maintenance level.
WLM modifies the thread dispatching by using recalculated process priorities instead of using static priorities assigned by the system. These priorities are calculated from current usage for all processes every second, broken down by WLM classes. WLM configuration assigns different shares of system resources to each class. It calculates the priorities to correct imbalances between desired and achieved resource share.
AIX WLM can control processor, memory and disk I/O bandwidth. WLM does not control network bandwidth. It is possible, and popular, to restrict WLM to controlling processor use alone.
WLM can run in "passive" mode, where it records resource utilization, but does not control it, that is, run in "active" mode, where it adjusts the priorities to desired resource utilization.