A mechanism is provided for optimizing energy efficiency in a set of processor cores while maintaining application performance for a set of applications. A quality of service (QoS) level is received for one or more active applications in the set of applications and state information associated with each processor core in the set of processor cores is identified. Responsive to the QoS level and the state information indicating an action to be implemented, a change is implemented to reduce power utilization by one or more processor cores in the set of processor cores in the data processing system, where the change is via at least one of dynamic frequency scaling, dynamic voltage scaling, or core folding.