Dynamic budget management and budget reclamation for mixed-criticality systems

Many existing studies on mixed-criticality (MC) scheduling assume that low-criticality budgets for high-criticality applications are known apriori. These budgets are primarily used as guidance to determine when the scheduler should switch the system mode from low to high. Based on this key observation, in this paper we propose a dynamic MC scheduling model under which low-criticality budgets for individual high-criticality applications are determined at runtime based on a system-wide total low-criticality budget allocation for all the high-criticality applications combined. This total budget is used as guidance in our model to determine the need for a mode-switch. At run time, a job may terminate prior to its allocated low-criticality budget, and hence the remaining low-criticality budget is wasted. Therefore, in the paper, we also propose a budget reclamation scheme that can work along with the dynamic model to further prevent the occurrence of mode-switch.