1. In a computer system having plural CPUs, including a timekeeping CPU and one or more non-timekeeping CPUs, operatively coupled to one or more memory devices, said system running an adaptive tick kernel, a method for detecting full-system idle state in said adaptive-tick kernel, comprising detecting a non-timekeeping CPU idle state, initiating a hysteresis period, waiting for said hysteresis period to end, manipulating a data structure whose state indicates whether a scheduling clock tick may be disabled on all of said CPUs, and disabling said scheduling clock tick on all of said CPUs if said data structure is determined to be in an appropriate state.