On Dynamic Thermal Conditions in Mixed-Criticality Systems

The rising demand for powerful embedded systems to support modern complex real-time applications signifies the on-chip temperature challenges. Heat conduction between CPU cores interferes in the execution time of tasks running on other cores. The violation of thermal constraints causes timing unpredictability to real-time tasks due to transient performance degradation or permanent system failure. Moreover, dynamic ambient temperature affects the operating temperature on multicore systems significantly.In this paper, we propose a thermal-aware server framework to safely upper-bound the maximum operating temperature of multi-core mixed-criticality systems. With the proposed analysis on the impact of ambient temperature, our framework manages mixed-criticality tasks to satisfy both thermal and timing requirements. We present techniques to find the maximum ambient temperature for each criticality level to guarantee the safe operating temperature bound. We also analyze the minimum time required for a criticality mode change from one level to another. The thermal properties of our framework have been evaluated on a commercial embedded platform. A case study with real-world mixed-critical applications demonstrates the effectiveness of our framework in bounding operating temperature under dynamic ambient temperature changes.