ER-EDF: A QoS Scheduler for Real-Time Embedded Systems

The increasing demand for embedded multimedia applications makes evident the need for end-to-end quality of service (QoS) provisioning. Particularly, operating systems, despite their location at end systems, switches or routers, must guarantee that resources under their control are adequately managed to fulfill the application requirements. This work proposes the implementation of QoS provisioning in real-time embedded systems scheduler. In order to achieve the end-to-end QoS, we propose the implementation of the control and management of QoS mechanisms in the operating system scheduler. The implementation of such mechanisms includes admission control and resource reservation, as well as process scheduling control and active monitoring of the delivered QoS. As a result, a new scheduling algorithm, named ER- EDF, is proposed and compared to previous scheduler solutions. This approach was validated through a set of benchmarks and we conclude that ER-EDF adds performance and simplified hard real-time support to realtime embedded applications.

[1]  Michael B. Jones,et al.  An overview of the Rialto real-time architecture , 1996, EW 7.

[2]  Jane W.-S. Liu,et al.  Scheduling real-time applications in an open environment , 1997, Proceedings Real-Time Systems Symposium.

[3]  Hermann de Meer,et al.  A survey of programmable networks , 1999, CCRV.

[4]  Giorgio C. Buttazzo,et al.  Resource Reservation in Dynamic Real-Time Systems , 2004, Real-Time Systems.

[5]  Jane W.-S. Liu.  Real-Time Systems , 2000, Encyclopedia of Algorithms.

[6]  Klara Nahrstedt,et al.  CPU service classes for multimedia applications , 1999, Proceedings IEEE International Conference on Multimedia Computing and Systems.

[7]  Haifeng Zhu,et al.  Diff-EDF: a simple mechanism for differentiated EDF service , 2005, 11th IEEE Real Time and Embedded Technology and Applications Symposium.

[8]  Klara Nahrstedt,et al.  A Soft Real Time Scheduling Server in UNIX Operating System , 1997, IDMS.

[9]  Jason Nieh,et al.  The design, implementation and evaluation of SMART: a scheduler for multimedia applications , 2001 .

[10]  Klara Nahrstedt,et al.  R-EDF: a reservation-based EDF scheduling algorithm for multiple multimedia task classes , 2001, Proceedings Seventh IEEE Real-Time Technology and Applications Symposium.

[11]  Stefan Savage,et al.  Processor capacity reserves: operating system support for multimedia applications , 1994, 1994 Proceedings of IEEE International Conference on Multimedia Computing and Systems.

[12]  Chung Laung Liu,et al.  Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment , 1989, JACM.

[13]  Michael B. Jones,et al.  CPU reservations and time constraints: efficient, predictable scheduling of independent activities , 1997, SOSP.