Scheduling Mixed-Criticality Real- Time Tasks with Fault Tolerance

Enabling computer tasks with different levels of criticality running on a common hardware platform has been an increasingly important trend in the design of real-time and embedded systems. On such systems, a real-time task may exhibit different WCETs (Worst Case Execution Times) in different criticality modes. It has been well-known that traditional realtime scheduling methods are not applicable to ensure the timely requirement of the mixed-criticality tasks. In this paper, we study a problem of scheduling real-time, mixed-criticality tasks with fault tolerance. An off-line algorithm is proposed to enhance the performance of the system when it runs into a highcriticality mode from a low-criticality mode. A novel on-line slack-reclaiming algorithm is also proposed to recover from as many faults as possible before the jobs’ deadline. Our simulations show that an improvement of about 30% in performance can be seen between our algorithm and a regular slack-reclaiming method.