A METHOD, APPARATUS, AND SYSTEM FOR ENERGY EFFICIENCY AND ENERGY CONSERVATION INCLUDING OPTIMIZING C-STATE SELECTION UNDER VARIABLE WAKEUP RATES

摘要

A processor may include power management techniques to, dynamically, chose an optimal C-state for the processing core. The measurement of real workloads on the OSes exhibit two important observations (1 ) the bursts of high interrupt rate are interspersed between the low interrupt rate periods and long periods of high activity levels; and (2) the interrupt rate may, suddenly, fall below an interrupt rate (of 1 milli-second, for example) that is typical of the current operating systems (OS). Instead of determining the C-state based on the stale data stored in the counters, the power control logic may determine an optimal C-state by overriding the C-state determined by the OS or any other power monitoring logic. The power control logic may, dynamically, determine an optimal C-state based on the CPU idle residency times and variable rate wakeup events to match the expected wakeup event rate.