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Journal of Information Science and Engineering, Vol. 23 No. 5, pp. 1349-1365 (September 2007)

Event-Driven Dynamic Workload Scaling for Uniprocessor Real-Time Embedded Systems*

Li-Pin Chang and Ya-Shu Chen+
Department of Computer Science
National Chiao Tung University
Hsinchu, 300 Taiwan
+Department of Electrical Engineering
National Taiwan University of Science and Technology
Taipei, 106 Taiwan

Many embedded systems are designed to take timely reactions to the occurrences of particular scenarios. Such systems could sometimes experience transient overloads because of workload bursts or hardware malfunctions. Thus a mechanism to focus limited resources on the processing of urgent events is a key to retain system validity under stressing workloads. In this paper, we propose a new approach for workload scaling in uniprocessor real-time embedded systems. The idea is to view the system as a black box, and workload scaling for overload management can be done via very intuitive primitives, i.e., how hardware events are selectively fed into the system. Such a new approach removes the need for the adjustments of task periods and task phasing, which is important for many workload-scaling techniques. The proposed approach is implemented in a real-time surveillance system. Experimental results show that the system still delivers good accuracy and high responsiveness for visual-object tracking under the presence of overloads.

Keywords: embedded systems, real-time systems, adaptive applications, overload management, real-time surveillance

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Received November 15, 2006; accepted February 15, 2007.
Communicated by Sung Shin and Tei-Wei Kuo.
*This work was partly supported by the National Science Council of Taiwan, R.O.C., under grant No. 95-2221-E-009-063. This paper is an extended version of the paper in [21].