Title: Optimal two-level speed assignment for real-time systems

Authors: Enrico Bini, Claudio Scordino

Addresses: Scuola Superiore Sant'Anna Via G. Moruzzi 1, 56124, Pisa, Italy. ' Evidence Srl, Via Carducci 64/A, 56010 Pisa, Italy

Abstract: Reducing energy consumption is one of the main concerns in the design and implementation of embedded real-time systems. For this reason, the current generation of processors allows to vary voltage and operating frequency to balance computational speed and energy consumption. This technique is called dynamic voltage scaling (DVS). When applying DVS to hard real-time systems, it is important to provide the worst-case computational requirement; otherwise the timing constraints may be violated. However, the probability of a task executing for its worst-case execution time is very low. In this paper, we show how to exploit probabilistic information about the execution time of a task in order to reduce the energy consumed by the processor. Optimal speed assignments and transition points are found using a very general model for the processor. The model accounts for the processor idle power and time/energy overheads due to frequency transitions. We also show how these results apply to some significant cases.

Keywords: dynamic voltage scaling; DVS; real-time; real-time systems; embedded systems; power-aware computing; probabilistic execution time; energy consumption; computational speed.

DOI: 10.1504/IJES.2009.027935

International Journal of Embedded Systems, 2009 Vol.4 No.2, pp.101 - 111

Available online: 20 Aug 2009 *

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