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Journal of Signal Processing Systems

, Volume 52, Issue 1, pp 45–57 | Cite as

A Dynamic Voltage Scaling Algorithm for Dynamic Workloads

  • Albert Mo Kim ChengEmail author
  • Yan Wang
Article

Abstract

Dynamic Voltage Scaling (DVS) is a promising method to achieve energy saving by slowing down the processor into multiple frequency levels in battery-operated embedded systems. However, the worst case execution time (WCET) of the tasks scheduled by DVS must be known ahead of time to ensure their schedulability. In reality, a system’s workloads may change significantly without satisfying any prediction. In other words, a task’s WCET may not provide useful information about its future real execution time (RET). This paper presents a novel Dynamic-Mode EDF scheduling algorithm when workloads change significantly. One of the Single-Mode, Dual-Mode, and Three-Mode frequency setting formats can be applied, based on the RET and the accumulated slack at run-time. Only one combination of the number of modes/speeds, speed-switching transition points, and the frequency scaling factor for each mode can lead to the best energy saving. Experimental results show that, given an RET pattern, our Dynamic-Mode DVS algorithm achieves an average 15% energy savings over the traditional two-mode DVS scheme on hard real-time systems. Additionally, we also consider speed-switching or energy transition overhead, and implement a preliminary test of our proposed algorithm. With a less aggressive voltage scaling strategy (fewer speed changes for each job), deadlines can still be strictly satisfied and an average of 14% energy consumption saving over a non-DVS scheme is observed.

Keywords

dynamic voltage scaling (DVS) power-aware computing scheduling dynamic workloads  real-time systems 

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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.Real-Time Systems Laboratory, Department of Computer ScienceUniversity of HoustonHoustonUSA

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