Quality of Service Scheduling in Real-Time Systems


  • Audrey Marchand University of Nantes Laboratoire d’Informatique de Nantes Atlantique 2, rue de la Houssinií¨re - BP 92208 44322 Nantes Cedex 03, FRANCE E-mail:
  • Maryline Chetto University of Nantes Institut de Recherche en Communications et Cybernétique de Nantes 1, rue de la Noe 44321 Nantes Cedex 03 FRANCE


real-time, dynamic scheduling, quality of service, periodic tasks, component-based systems, Linux-based systems


In this paper, we deal with dynamic scheduling components integrating new Quality of Service (QoS) functionalities into a Linux-based real-time operating system. In our approach, periodic tasks allow occasional deadline violations within given bounds specified according to the Skip-Over task model. Hence, every task has a minimal QoS guarantee which is expressed by the ratio of periodic task instances which must complete before their deadline. The work stated here provides two on-line scheduling algorithms, namely RLP and RLP/T, which enhance the existing Skip-Over algorithms. More specifically, the proposed algorithms aim at improving the actual QoS observed for periodic tasks (which is always greater or equal to the QoS guarantee). These novel scheduling techniques rely on the EDL (Earliest Deadline as Late as possible) scheduling strategy. Simulation results show the performance of RLP and RLP/T with respect to basic Skip-Over algorithms. Finally, we present the integration of these QoS scheduling services into CLEOPATRE open-source component library, a patch to Linux/RTAI.


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