At the Low-Power Systems Institute, we are working on the development of technologies for reducing the power consumption of notebook computers from the system-level point of view. Our results are used to extend the battery life and reduce the heat dissipation of IBM's ThinkPad line of notebook computers.
On this page, we would like to introduce "Portable Power Analysis and Recording Tool" as an example of our projects.
- Portable Power Analysis and Recording Tool (PoPART)
In normal usage, notebook computers have many short periods of idle time. If we can put idling CPUs and devices into power-saving modes, the total power consumption can be greatly reduced. Even if each period of idle time is very short, the total reduction we can achieve is very significant, because cumulatively such idle periods account for the majority of the operating time: the battery life with power management is actually a couple of times longer than the battery life without power management. In other words, efficient power management is essential for extending the battery life.
To implement efficient power management, we first need to know exact details of the power consumption and system activities of notebook computers in actual usage. The right photograph shows the PoPART system, which was developed for measuring and analyzing them. By using PoPART (center) through a controller (left), we can measure the power consumption and system activities of a target machine (right) simultaneously. This makes it easy to analyze the power management and its effects.
- S. Shimotohno, "Power Management for Notebook PCs," Journal of the IPSJ, Vol.38, No.2, pp.135-142, in Japanese (1997).
- T. Aihara et al., "Low-Power System Technologies for Notebook Computers," Journal of the IEICE, Vol.80, No.4, pp.370-376, in Japanese (1997).
- S. Furuichi et al., "Application-Directed Power Management," Proc. 55th Annual Convention of the IPSJ, Vol.1, pp.139-140, in Japanese (1997).
- T.Aihara et al., "Job Type Categories for Power Saving," Proc. 55th Annual Convention of the IPSJ, Vol.1, pp.141-142, in Japanese (1997).
- T. Inoue et al., "Effect of External Cache on the Power Dissipation and Performance of Notebook Computers," Proc. 55th Annual Convention of the IPSJ, Vol.1, pp.141-142, in Japanese (1997).
- S. Furuichi et al., "Application-Oriented Power Management," IPSJ SIG Notes Vol.98, No.15, pp.135-140, in Japanese (1998).