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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2011, Vol. 32 ›› Issue (6): 1067-1074.doi: CNKI:11-1929/V.20101228.1347.007

• Avionics and Autocontrol • Previous Articles     Next Articles

Two-level Hierarchical Scheduling for Hybrid Real-time Tasks in Avionic Systems

ZHOU Tianran, XIONG Huagang   

  1. School of Electronics and Information Engineering, Beihang University, Beijing 100191, China
  • Received:2010-08-25 Revised:2010-10-21 Online:2011-06-25 Published:2011-06-24

Abstract: By considering the demand for real time performance in avionic systems, a two-level hierarchical scheduling algorithm is proposed for the integrated modular avionics (IMA) architecture. Each partition is assigned a dedicated time window and activated by the weighted round robin scheduling, which enhances the predictability of the system. Within the partition, the fixed priority preemptive scheduling is applied to reduce the response time of the tasks with higher priorities. The algorithm can be used for hybrid real-time task scheduling. For periodic hard real-time tasks, a task model with arbitrary dead-line is built to enhance its generality, and the schedulability conditions are derived under hierarchical scheduling by analyzing the response time bound. For aperiodic soft real-time tasks, the concept of expected schedulability is introduced to guarantee the real-time performance in statistics. The design and optimization of the partition parameters is also discussed, and a first fit method is proposed to solve the problem. The influence of the partition parameters on task scheduling is analyzed by simulations. This algorithm, which considers the hybrid real time task scheduling, has better erformance in generality.

Key words: aviation system engineering, integrated modular avionics (IMA), hierarchical scheduling, schedulability analysis, real-time systems

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