Scheduling Analysis of Imprecise Mixed-Criticality Real-Time Tasks

• Published in: IEEE transactions on computers Vol. 67; no. 7; pp. 975 - 991
• Main Authors: Di Liu, Nan Guan, Spasic, Jelena, Gang Chen, Songran Liu, Stefanov, Todor, Wang Yi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Analytical models; Computational modeling; imprecise model; mixed-criticality; Real-time systems; Safety; Scheduling; Scheduling algorithms; Task scheduling; Tuning
• ISSN: 0018-9340; 1557-9956
• DOI: 10.1109/TC.2018.2789879

In this paper, we study the scheduling problem of the imprecise mixed-criticality model (IMC) under earliest deadline first with virtual deadline (EDF-VD) scheduling upon uniprocessor systems. Two schedulability tests are presented. The first test is a concise utilization-based test which can be applied to the implicit deadline IMC task set. The suboptimality of the proposed utilization-based test is evaluated via a widely-used scheduling metric, speedup factors. The second test is a more effective test but with higher complexity which is based on the concept of demand bound function (DBF). The proposed DBF-based test is more generic and can apply to constrained deadline IMC task set. Moreover, in order to address the high time cost of the existing deadline tuning algorithm, we propose a novel algorithm which significantly improve the efficiency of the deadline tuning procedure. Experimental results show the effectiveness of our proposed schedulability tests, confirm the theoretical suboptimality results with respect to speedup factor, and demonstrate the efficiency of our proposed algorithm over the existing deadline tunning algorithm. In addition, issues related to the implementation of the IMC model under EDF-VD are discussed.