Scheduling periodic and aperiodic tasks with time, energy harvesting and precedence constraints on multi-core systems

This paper deals with the real-time scheduling problem of multi-core systems powered by renewable energy harvested from environment. They handle two types of software tasks which are mapped to cores statically and not allowed to migrate. A task can be periodic which may depend on other tasks’ results, or aperiodic which is added to the system to cope with external interruptions. The uncertainty of energy availability in energy harvesting systems makes real-time scheduling more challenging because energy constraints can be violated to ensure real-time performance. A novel scheduling strategy is proposed to effectively compute deadlines allowing for tasks and messages to meet related constraints. This method consists of two phases, (i) the first one defines different time slots each of which is characterized by energy and frequency parameters to cope with the energy availability issue, and (ii) the second one calculates the deadlines ensuring real-time system feasibility by considering the invocation of aperiodic task execution and task precedence constraints. The originality of the current work compared with related studies is that it deals with multi-core, periodic and aperiodic tasks, dependency, energy harvesting, and real-time aspects simultaneously.