1. A method, in a data processing system, for adjusting an operational state of the data processing system so as to achieve a target time period of operation when the data processing system is using a depleting power supply, the method comprising: determining a predicted power consumption of individual processes executing on the data processing system; determining a remaining amount of power that the depleting power supply can provide; identifying a subset of processes whose execution can be suspended so that the data processing system can operate for the target period of time based on the predicted power consumption of the individual processes and the amount of power that the depleting power supply can provide; and placing the identified subset of processes in a suspended execution state.