One of the fundamental changes in our field in recent years has been the increasing use of platform operating systems in the embedded world. The majority of ARM-based systems these days, large and surprisingly small, will use either one of the many proprietary real-time operating systems available or will use a home-brewed scheduler of some kind. Except at the small end, the people who develop the applications are generally not the same people as those who develop the operating systems under which they run. Both groups of engineers, though, need increasingly to focus on being energy-efficient.