Enhanced Schedulability Tests for Real-Time Regularity-Based Virtualized Systems with Dependent and Self-Suspension Tasks

As virtualization becomes increasingly popular, more critical applications that require real-time performance guarantees are deployed on virtualized systems. In such systems, the Hierarchical Real-Time Scheduling (HiRTS) framework divides the scheduling problem into task-level scheduling and resource-level scheduling. Specifically, resource-level scheduling divides a physical resource into multiple resource partitions while task-level scheduling schedules the tasks on each resource partition. Accordingly, the Regularity-based Resource Partitioning (RRP) model offers efficient resource-level scheduling. Despite the availability of adequate resource-level tools, the task-level scheduling based on the RRP model still has a scope for improvements. To extend the applicability of the RRP model under a variety of task workload environments, this paper offers: (1) a more practical schedulability test for independent tasks whose key parameters, i.e., Worst-Case Execution Time (WCET), period and deadline, are non-integral multiples of a time slice; (2) a tuned Earliest Deadline First (EDF) scheduling approach and a corresponding schedulability test for intra-VM dependent tasks; (3) schedulability tests for self-suspended tasks based on Fixed-Relative-Deadline (FRD) scheduling strategies.