The Design and Analysis of Thermal-Resilient Hard-Real-Time Systems

We address the challenge of designing predictable real-time systems in an unpredictable thermal environment where environmental temperature may dynamically change (e.g., implantable medical devices). Towards this challenge, we propose a control-theoretic design methodology which permits a system designer to specify a set of hard-real-time performance modes under which the system may operate. The system automatically adjusts the real-time performance mode based on the external thermal stress. We show (via analysis, simulations, and a hardware testbed implementation) that our control-design framework is stable and control performance is equivalent to previous real-time thermal approaches, even under dynamic temperature changes. A crucial and novel advantage of our framework over previous real-time control is the ability to guarantee hard deadlines even under transitions between modes. Furthermore, our system design permits the calculation of a new metric called thermal resiliency which characterizes the maximum external thermal stress that any hard-real-time performance mode can withstand. Thus, our design framework and analysis may be classified as a thermal stress analysis for real-time systems.