A hybrid scheduling scheme for hard, soft and non-real-time tasks

This paper proposes a hybrid scheduling scheme for hard, soft and non-real-time tasks. The scheme creates a constant utilization server for each real-time scheduling policy and a total bandwidth server for all the non-real-time tasks with time sharing scheduling policy. Each server has a scheduler, called server scheduler, which is responsible for executing the ready-to-run tasks with the same scheduling policy as the server. All the servers are scheduled by the bottom operating system scheduler according to EDF algorithm. The schedulability test is also presented in this paper. The hybrid scheme can be used to implement different real time systems with different goals (such as hard, soft or hybrid real-time systems) and can provide the real-time services with different QoS to the different task modes by adjusting every constant utilization server´s size. This scheme also simplifies the schedulability analysis and validates the schedulability of the tasks with one scheduling policy independently of the tasks with other scheduling policies. The experimental results show that the hybrid scheme is an efficient scheduling scheme