Quality of Service Scheduling in Real-Time Systems

Audrey Marchand (1) , Maryline Chetto (2)

1 LINA - Laboratoire d'Informatique de Nantes Atlantique
2 IRCCyN - Institut de Recherche en Communications et en Cybernétique de Nantes

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.

Mots clés: real-time; dynamic scheduling; quality of service; periodic tasks; component-based systems; Linux-based systems

Domaines: Système d'exploitation [cs.OS]

Audrey Marchand, Maryline Chetto. Quality of Service Scheduling in Real-Time Systems. International Journal of Computers, Communications and Control, 2008, 3 (4), pp.354-366. ⟨hal-00464219⟩