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The Power Manager is responsible for managing power usage for the system. It administers the system-wide power policy and tracks the path of power IRPs through the system.
The Power Manager requests power operations by sending IRP_MJ_POWER requests to drivers. A request can specify a new power state or can query whether a change in power state is feasible.
When sleep, hibernation, or shutdown is required, the Power Manager sends an IRP_MJ_POWER request to each leaf node in the device tree requesting the appropriate power action. The Power Manager considers the following in determining whether the system should sleep, hibernate, or shut down: