DYNAMIC CLOCK CONTROL FOR MICROPROCESSOR SYSTEM ENERGY MANAGEMENT
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-20
When a microprocessor-based system is controlled by Operating System software that has task prioritization capabilities, a lower level task is executed when higher level tasks are idle. For energy conservation purposes, the lowest level task should put the processor into some idle, low-power mode. When the lowest level task is reached (all other tasks are idle) a large portion of the operating time of the system, this indicates that the clock rate of the microprocessor can be slowed down to con- serve energy without sacrificing system performance. When the system is operating at its low speed and the lowest level task is only reached a very small portion of the time (or possibly never), this indicates that the pro- cessor may not be performing the low-level tasks often enough to insure proper system performance, so the clock should be sped up. There may also be identifiable "critical" operations which require the processor to oper- ate at the highest possible speed to ensure performance compliance; clock control should be disabled for the duration of the "critical" operation.