Precise scheduling of mixed-criticality tasks by varying processor speed

Abstract

In this paper, we extend the imprecise mixed-criticality (IMC) model to precise scheduling of tasks. We also integrate the IMC model with the dynamic voltage and frequency scaling (DVFS) technique to enable energy minimization. The challenge in precise scheduling of MC systems is to guarantee the timing correctness all tasks under both pessimistic and optimistic assumptions simultaneously. To our knowledge, this is the first work to address the integration of DVFS energy-conserving techniques with precise scheduling of all tasks of the MC model. We present utilization based schedulability tests and sufficient conditions for such systems under two well-known MC frameworks, EDF-VD and MCF. A quantitative study in the forms of speedup bound and approximation ratio are derived for the unified model. Empirical studies based on randomly generated sets are conducted to verify the theoretical results as well as the effectiveness of the proposed algorithms.