1. A high performance computing system comprising: a plurality of nodes, each such node configurable to operate within a given power range, two or more of the plurality of nodes configurable to execute an application program; and a power controller operatively coupled with the two or more nodes to dynamically control power consumption of the two or more nodes by: receiving, from the application program, first power commands relative to the two or more nodes executing the application program; in response to receiving the first power commands, changing the power range for the two or more nodes executing the application program from the given power range to a first new power range, each of the two or more nodes thereafter executing the application program while operating within the first new power range; receiving, from the application program, second power commands relative to the two or more nodes executing the application program; and in response to receiving the second power commands, changing the power range for the two or more nodes executing the application program from the first new power range to a second new power range, each of the two or more nodes thereafter executing the application program while operating within the second new power range.