Task schedulability analyzing method of two-level hierarchical scheduling algorithm in integrated modular avionics

The task schedulability analysis on the two-level hierarchical scheduling algorithm in integrated modular avionics (IMA) is a key issue. As for this problem, this paper firstly dissects the method of calculating a task's exact response time and we learn that this method is limited by its features of high calculating complexity and non-continuity. To overcome these limitations, a method of calculating a task's upper bound response time is proposed. Further analyzing the method's deducing process, we achieve the formulation of calculating the response upper bound of a task under two-level hierarchical scheduling. Moreover, a task schedulability analysis method and partition parameters' designing method are inferred from the formulation. Finally, we deeply investigate how the factors, including the number of all the system tasks and the system utilization, would affect the precision of the upper bound response time calculating method proposed ahead using a quantitative analysis method of upper bound response time relative error and a qualitative analysis method of resource augmentation analyzing respectively. And the practical requirements of obtaining relatively high precision are acquired when applying this method.