Dynamic Power Management
Dynamic Power Management

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Dynamic Power Management

Introducing DPM

The Dynamic Power Management (DPM) project explores technologies to improve power conservation capabilities of platforms based on open source software. Of particular interest are techniques applicable to running systems, adjusting power parameters on-the-fly while ensuring realtime deadlines of running software are met. DPM software exploits recent advances in hardware to scale clocking information (such as CPU and core bus frequencies) and core voltages with low latency. This allows these parameters to be adjusted very frequently in order to realize power savings during brief idle periods or execution of tasks with lower performance and power demands. Our work so far targets the Linux operating system and the characteristics of hardware used for embedded Linux. Ongoing DPM investigations are attuned to the requirements of vendors of consumer electronics devices, such as the members of the Consumer Electronics Linux Forum, and embedded silicon vendors who have requested enhanced power management capabilities for Linux.

The DPM project results from a collaboration between the IBM Austin Research Lab and MontaVista Software.

The Sourceforge DPM Project We hope to spark community interest to improve the dynamic properties of Linux power management, as well as to investigate and implement further power management features for embedded environments. We also hope to begin discussion on how to integrate these ideas with other power management technologies and community efforts such as the Linux-2.6 PM and sysfs infrastructure, the cpufreq interfaces and drivers for setting CPU frequencies, ACPI-based systems, and so forth.
Ongoing work

Among the present and planned activities for DPM are:

  • Adding support for more platforms.

  • Integrating dynamic power management with standby/suspend/hibernate low-power states, and extending ACPI-inspired standby support for embedded devices that feature a variety of low-power "sleep" states.

  • Power policy management for tightly integrated application environments on consumer electronics devices, allowing the system designer precise control over numerous platform power parameters.

  • Automated power policy management that automatically selects desired power parameters based on system state, such as CPU load.

  • Reliably suspend and resume devices actively in use at suspend time through staged calls into drivers to suspend and lockout of new requests during a suspend period.

  • Integrate management of platform power parameters with device requirements, scaling device power parameters or powering off devices in response to platform changes that affect operation of devices. Possibly constrain power state transitions based on the needs of devices actively in use.

  • Very fast application restart on resume while slower, hotplug-capable devices are rescanned.