Running state power saving via reduced instructions per clock operation

摘要

A microprocessor includes functional units and control registers writeable to cause the functional units to institute actions that reduce the instructions-per-clock rate of the microprocessor to reduce power consumption when the microprocessor is operating in its lowest performance running state. Examples of the actions include in-order vs. out-of-order execution, serial vs. parallel cache access and single vs. multiple instruction issue, retire, translation and/or formatting per clock cycle. The actions may be instituted only if additional conditions exist, such as residing in the lowest performance running state for a minimum time, not running in a higher performance state for more than a maximum time, a user did not disable the feature, the microprocessor supports multiple running states and the operating system supports multiple running states.

主权项

1. A microprocessor configured to transition through a plurality of performance running states, ranging between lowest and highest, each comparatively characterized by differences in clock frequencies and/or voltage levels, the microprocessor comprising:
functional units; and control registers, writeable to cause the functional units to institute one or more power-saving actions that reduce the instructions-per-clock rate of the microprocessor to reduce power consumption when the microprocessor is operating in its lowest performance running state; wherein the lowest performance running state comprises a non-sleeping state in which the microprocessor runs at its lowest supported clock frequency; wherein the microprocessor is configured with microcode to write the control registers to institute the one or more instructions-per-clock rate reducing actions, wherein the microcode is invoked in response to an instruction instructing the microprocessor to transition to the lowest performing running state.