Feedback Thermal Control for Real-time Systems

Thermal control is crucial to real-time systems as excessive processor temperature can cause system failure or unacceptable performance degradation due to hardware throttling. Real-time systems face significant challenges in thermal management as they must avoid processor overheating while still delivering desired real-time performance. Furthermore, many real-time systems must handle a broad range of uncertainties in system and environmental conditions. To address these challenges, this paper presents Thermal Control under Utilization Bound (TCUB), a novel thermal control algorithm specifically designed for real-time systems. TCUB employs a nested feedback loop that dynamically controls both processor temperature and CPU utilization through task rate adaptation. Rigorously modeled and designed based on control theory, TCUB can maintain both desired processor temperature and CPU utilization, thereby avoiding processor overheating and maintaining desired soft real-time performance. A salient feature of TCUB lies on its capability to handle a broad range of uncertainties in terms of processor power consumption, task execution times, ambient temperature, and unexpected thermal faults. The robustness of TCUB makes it particularly suitable for real-time embedded systems that must operate in highly unpredictable environments. The advantages of TCUB are demonstrated through extensive simulations under a broad range of system and environmental uncertainties.