1. A method for transitioning a processing unit to a target power-state, the method comprising: monitoring one or more of: active-state residency of the processing unit; non-active-state residency of the processing unit; Direct Memory Access (DMA) transfer activity associated with the processing unit; Input/Output (I/O) processes associated with the processing unit; or a value of a timer-tick (TT) interval associated with the processing unit; deriving status information from said monitoring; and determining based on the status information whether to allow the processing unit to transition to the target power-state.