Resource Sharing in Multicore Mixed-Criticality Systems: Utilization Bound and Blocking Overhead

Abstract

In mixed-criticality (MC) system, diverse application activities with various certification requirements (different criticality) can share a computing platform, where multicore processors have emerged as the prevailing computing engines. Focusing on the problem of resource access contention in multicore MC systems, we analyze the synchronization issues and blocking characteristics of the Multiprocessor Stack Resource Policy (MSRP) with both priority and criticality inversions among MC tasks being considered. We develop the first criticality-aware utilization bound under partitioned Earliest Deadline First (EDF) and MSRP by taking the worst case synchronization overheads of tasks into account. The non-monotonicityof the bound where it may decrease when more cores are deployed is identified, which can cause anomalies in the feasibility tests. With the objective to improve system schedulability, a novel criticality-cognizant and resource-oriented analysis approach is further studied to tighten the bound on the synchronization overheads for MC tasks scheduled under partitioned EDF and MSRP. The simulation results show that the new analysis approach can effectively reduce the blocking times for tasks (up to 30 percent) and thus improve the schedulability ratio (e.g., 10 percent more). The actual implementation in Linux kernel further shows the practicability of partitioned-EDF with MSRP (with run-time overhead being about 3 to 7 percent of the overall execution time) for MC tasks running on multicores with shared resources.