Battery-conscious task sequencing for portable devices including voltage/clock scaling

ABSTRACT

Operation of battery-powered portable systems can no longer be sustained once a battery becomes discharged. Maximization of the battery lifetime is a difficult task due to nonlinearity of battery behavior that depends on the characteristics of the system load profile. We address the problem of task sequencing without and with voltage/clock scaling that shapes the profile so that the battery lifetime is maximized. We developed an accurate analytical battery model and validated it with measurements taken on a real lithium-ion battery used in a pocket computer. We use the model as a basis for a unique battery conscious cost function and utilize its properties to develop several novel algorithms, including insertion of recovery periods and voltage/clock scaling for delay slack distribution.

REFERENCES

• 1: L. Benini , G. Castelli , A. Macii , E. Macii , M. Poncino , R. Scarsi, A discrete-time battery model for high-level power estimation, Proceedings of the conference on Design, automation and test in Europe, p.35-41, March 27-30, 2000, Paris, France [doi>10.1145/343647.343694]
• 2: Luca Benini , Giuliano Castelli , Alberto Macii , Riccardo Scarsi, Battery-Driven Dynamic Power Management, IEEE Design & Test, v.18 n.2, p.53-60, March 2001 [doi>10.1109/54.914621]
• 3: Robert W. Brodersen, Energy Efficient Microprocessor Design, Kluwer Academic Publishers, Norwell, MA, 2001
• 4: D. Linden. Handbook of Batteries. McGraw-Hill, New York, 1995.
• 5: Jinfeng Liu , Pai H. Chou , Nader Bagherzadeh , Fadi Kurdahi, Power-aware scheduling under timing constraints for mission-critical embedded systems, Proceedings of the 38th conference on Design automation, p.840-845, June 2001, Las Vegas, Nevada, United States [doi>10.1145/378239.379076]
• 6: Jiong Luo , Niraj K. Jha, Battery-aware static scheduling for distributed real-time embedded systems, Proceedings of the 38th conference on Design automation, p.444-449, June 2001, Las Vegas, Nevada, United States [doi>10.1145/378239.378553]
• 7: Thomas L. Martin , Daniel P. Siewiorek, Balancing batteries, power, and performance: system issues in cpu speed-setting for mobile computing, 1999
• 8: Massoud Pedram , Qing Wu, Design considerations for battery-powered electronics, Proceedings of the 36th ACM/IEEE conference on Design automation, p.861-866, June 21-25, 1999, New Orleans, Louisiana, United States [doi>10.1145/309847.310089]
• 9: D. Rakhmatov, S. Vrudhula, and D. Wallach. A model for battery lifetime analysis for organizing applications on a pocket computer. To appear IEEE Trans. VLSI Systems.
• 10: M. Viredaz and D. Wallach. Power evaluation of a handheld computer: a case study. Compaq WRL Research Report 2001/1, May 2001.

INDEX TERMS

Primary Classification:
  J. Computer Applications
  J.6 COMPUTER-AIDED ENGINEERING

General Terms:
Algorithms, Design, Performance

Keywords:
battery, low-power design, modeling, scheduling, voltage scaling