Power Management Framework

The Solaris Power Management framework depends on device drivers to implement device-specific power management functionality. The framework is implemented in two parts:

• Device power management - Automatically turns off unused devices to reduce power consumption.

• System power management - Automatically turns off the computer when the entire system is idle.

Device Power Management

The framework allows devices to reduce their energy consumption after a specified idle time interval. To perform effective device power management, system software monitors the different devices and determines when they are not in use. Since only device drivers are able to determine when a device is idle, and only device drivers are able to reduce power consumption of a device, the Power Management framework exports interfaces to enable communication between the system software and the device driver.

The Solaris Power Management framework provides the following:

• A device-independent model for power-manageable devices

• System software to implement a power management policy (which is controlled by a user-modifiable configuration file)

• A set of DDI interfaces for the device driver to notify the framework if the device can be power managed, and when it is idle or busy

System Power Management

System power management consists of turning off the entire computer after saving its state so that it can be returned to the same state immediately when it is turned back on.

To shut down an entire system and later return it to the state it was in prior to the shutdown, it is necessary to:

• Stop (and later restart) kernel threads and user processes.

• Save the hardware state of all devices on the system to disk (and later restore it).

System power management is currently implemented only on some SPARC systems supported by the Solaris 8 operating environment.

The Solaris operating environment System Power Management framework provides the following:

• A platform-independent model of system idleness.

• System software to implement a system power management policy (which is controlled by a user-modifiable configuration file).

• A set of interfaces for the device driver to override the method for determining which drivers have hardware state.

• A set of interfaces to allow the framework to call into the driver to save and restore the device state.

• A mechanism for notifying processes that a resume operation has occurred.