Energy efficient scheduler of aperiodic jobs for real-time embedded systems
Energy consumption has become a key metric for evaluating how good an embedded system is, alongside more performance metrics like respecting operation deadlines and speed of execution. Schedulability improvement is no longer the only metric by which optimality is judged. In fact, energy efficiency is becoming a preferred choice with a fundamental objective to optimize the system’s lifetime. In this work, we propose an optimal energy efficient scheduling algorithm for aperiodic real-time jobs to reduce CPU energy consumption. Specifically, we apply the concept of real-time process scheduling to a dynamic voltage and frequency scaling (DVFS) technique. We address a variant of earliest deadline first (EDF) scheduling algorithm called energy saving-dynamic voltage and frequency scaling (ES-DVFS) algorithm that is suited to unpredictable future energy production and irregular job arrivals. We prove that ES-DVFS cannot attain a total value greater than C/000000, where 000000 is the minimum speed of any job and C is the available energy capacity. We also investigate the implications of having in advance, information about the largest job size and the minimum speed used for the competitive factor of ES-DVFS. We show that such advance knowledge makes possible the design of semi-on-line algorithm, ES-DVFS**, that achieved a constant competitive factor of 0.5 which is proved as an optimal competitive factor. The experimental study demonstrates that substantial energy savings and highest percentage of feasible job sets can be obtained through our solution that combines EDF and DVFS optimally under the given aperiodic jobs and energy models.
KeywordsReal-time systems energy efficiency aperiodic jobs scheduling dynamic voltage scaling low-power systems embedded systems
Unable to display preview. Download preview PDF.
- H. Zeng, C. S. Ellis, A. R. Lebeck, A. Vahdat. ECOSystem: Managing energy as a first class operating system resource. In Proceedings of the 10th International Conference on Architectural Support for Programming Languages and Operating Systems, ACM, New York, USA, pp. 123–132, 2002.Google Scholar
- M. Weiser, B. Welch, A. Demers, S. Shenker. Scheduling for reduced CPU Energy. In Proceedings of the 1st USENIX Conference on Operating Systems Design and Implementation, ACM, Berkeley, USA, 1994.Google Scholar
- S. Baruah, G. Koren, D. Mao, B. Mishra, A. Raghunathan, L. Rosier, D. Shasha, F. Wang. On the competitiveness of on-line real-time task scheduling. In Proceedings of the 12th IEEE Real-time Systems Symposium, IEEE, San Antonio, USA, pp. 106–115, 1991.Google Scholar
- M. L. Dertouzos. Control robotics: The procedural control of physical processes. In Proceedings of International Federation of Information Processing Congress, pp. 807–813, 1974.Google Scholar
- I. Hong, M. Potkonjak, M. B. Srivastava. On-line scheduling of hard real-time tasks on variable voltage processor. In Proceedings of the 1998 IEEE/ACM International Conference on Computer-Aided Design, IEEE, San Jose, USA, pp. 653–656, 1998.Google Scholar
- I. Hong, D. Kirovski, G. Qu, M. Potkonjak, M. Srivastava. Power optimization of variable voltage core-based systems. In Proceedings of IEEE Design Automation Conference, IEEE, San Francisco, USA, pp. 176–181, 1998.Google Scholar
- Y. Shin, K. Choi. Power conscious fixed priority scheduling for hard real-time systems. In Proceedings of the 36th IEEE Design Automation Conference, IEEE, New Orleans, USA, pp. 134–139, 1999.Google Scholar
- R. Jejurikar, R. Gupta. Optimized slowdown in real-time task systems. In Proceedings of the 16th IEEE EuroMicro Conference on Real-time Systems, IEEE, Catania, Italy, pp. 155–164, 2004.Google Scholar
- P. Pillai, K. G. Shin. Real-time dynamic voltage scaling for low-power embedded operating systems. In Proceedings of the 8th ACM Symposium on Operating Systems Principles, ACM, New York, USA, pp. 89–102, 2001.Google Scholar
- L. Thiele, S. Chakraborty, A. Maxiaguine. DVS for bufferconstrained architectures with predictable QoS-energy tradeoffs. In Proceedings of the 3rd IEEE/ACM/IFIP International Conference on Hardware/Software Codesign and System Synthesis, IEEE, Jersey City, USA, pp. 111–116, 2005.Google Scholar
- H. E. L. Ghor, E. H. M. Aggoune. Energy saving EDF scheduling for wireless sensors on variable voltage processors. International Journal of Advanced Computer Science and Applications, vol. 5 no. 2, pp. 158–167, 2014.Google Scholar
- J. W. S. W. Liu. Real-time Systems, NJ, USA: Prentice Hall, 2000.Google Scholar