A Real-Time Tasks Scheduling Algorithm Based on Dynamic Priority

Most of the existing real-time scheduling algorithms assign the priorities of tasks according to tasks' time and value,but few of them can synchronously consider the value and urgency of a task.In this paper,for a real-time task,we firstly discuss its dynamic value density according to its value and remainder execution time,and analyze its execution urgency by considering its deadline and spare time.Based on the dynamic value densities and execution urgencies of the real-time tasks,we propose a strategy named DPA to dynamically assign the priorities of the real-time tasks.Additionally,we also present a DPA-based scheduling algorithm named DTRP.For the algorithm,we analyze all the situations of preemptive scheduling,discuss the thrashing and the condition of avoiding the thrashing.The experimental results show that the DRTP algorithm is prior to other analogous algorithms on the accrual value of real-time system,the deadline miss ratio and the preemptive number.