[$] CPU frequency governors and remote callbacks

The kernel's CPU-frequency ("cpufreq") governors are charged with pickingan operating frequency for each processor that minimizes power use whilemaintaining an adequate level of performance as determined by the currentpolicy. These governors normally run locally, with each CPU handling itsown frequency management. The 4.14 kernel release, though, will enable theCPU-frequency governors to control the frequency of any CPU in thesystem if the architecture permits, a change that should improve theperformance of the system overall.