Component-Based Mixed-Criticality Real-Time Scheduling on a Single Processor System

Abstract

This paper focuses on a two-level hierarchical system with dual-criticality components scheduled on a single processor. To address the independent scheduling of mixed-criticality (MC) components using fixed-priority (FP) servers, we introduce the mixed-criticality deferrable server (MC-DS), featuring multiple server capacities within a fixed server period. Within the MC-DS, we employ the earliest deadline first (EDF) scheduler to manage mixed-criticality tasks for each component. We perform schedulability analysis based on the worst-case response time (WCRT) for MC-DSs. Augmented by the WCRT analysis, we derive a new supply bound function (SBF) to precisely evaluate the processor execution time guaranteed by the server for components over specific time intervals. Furthermore, a more effective schedulability test based on the concept of demand bound function – supply bound function (DBF-SBF) is presented. Through extensive experiments, we demonstrate the effectiveness of our proposed component-based schedulability analysis. Specifically, our method improves the acceptance ratio of task sets by an average of 17% in our experiments.

Keywords

• Earliest deadline first (EDF)
• fixed-priority (FP)
• hierarchical system
• real-time server
• mixed-criticality scheduling
• supply bound function (SBF)