1. A method of managing power consumption of a computer, the computer comprising a computer processor, the method comprising: dynamically during operation of the computer, setting, by an in-band power manager in dependence upon performance metrics of the computer processor, a current performance state (‘p-state’) of the computer processor, wherein the performance metrics of the computer processor include quantifiable measurements describing actual performance of the computer processor; providing, by the in-band power manager to an out-of-band power manager, the current p-state of the computer processor; and calculating, by the out-of-band power manager, in dependence upon currently-measured operating metrics of the computer processor, a power setpoint for the computer processor, and the current p-state, an operating state for the computer processor.