Method and apparatus for managing power in computer systems

A method for distributing management of power of a computer system, the method comprising:

• a) at a parent power manager, defining a power state of a parent power domain based on an output power characteristic of said parent power domain;
• b) changing said power state of the parent power domain to said defined power characteristic of said parent power domain;
• and
• c) after the changing, notifying a child power manager with data related to said changed parent power state, said child power manager being a power manager for a member of said parent power domain, said child power manager for determining a power state of the member based on the data related to the changed parent power state.

A computer readable medium storing a computer program, the computer program comprising sets of instructions for:

• a) at a parent power manager, defining a power state of a parent power domain based on an output power characteristic of said parent power domain;
• b) changing said power state of the parent power domain to said defined power characteristic of said parent power domain;
• and
• c) after the changing, notifying a child power manager with data related to said changed parent power state, said child power manager being a power manager for a member of said parent power domain, said child power manager for determining a power state of the member based on the data related to the changed parent power state.

A system comprising:

• a power domain and a member of the power domain;
• a first power manager and a second power manager;
• the second power manger for notifying the first power manager of a specified lower input power requirement, the second power manager being the power manager for the member of the power domain;
• and
• the first power manager for defining a power state of the power domain based on said input power requirement.

A system comprising:

• a power domain and a member of the power domain;
• a first power manager and a second power manager;
• the first power manager for defining and changing a power state of the power domain based on an output power characteristic of the power domain;
• and
• the second power manager for receiving a notification of said defined power state after said first power manager changes said power state, said second power manager being the power manager for a member of said power domain and for determining a power state of the member based on the data related to the changed parent power state.

A system comprising:

• a first power management member;
• a second power management member that derives power from the first power management member;
• a first power manager for (i) computing a power state of the first power management member, and (ii) changing the power state of the first power management member based on the computed power state for the first power management member;
• and
• a second power manager for (i) computing a power state of the second power management member, and (ii) changing the power state of the second power management member based on the computed power state for the second power management member when the power state of the first power management member is sufficient to satisfy the change to the power state of the second power management member.

A method comprising:

• at a first power manager, computing a power state of a first power management member;
• changing the power state of the first power management member based on the computed power state by the first power manager;
• at a second power manager, computing a power state of a second power management member, wherein the second power management member derives power from the first power management member;
• and
• changing the power state of the second power management member based on the computed power state by the second power manager when the power state at the first power management member is sufficient to satisfy the change to the power state of the second power management member.