  The design of cyber-physical systems (CPSs) faces various new challenges that
are unheard of in the design of classical real-time systems. Power optimization
is one of the major design goals that is witnessing such new challenges. The
presence of interaction between the cyber and physical components of a CPS
leads to dependence between the time delay of a computational task and the
amount of workload in the next iteration. We demonstrate that it is essential
to take this delay-workload dependence into consideration in order to achieve
low power consumption.
  In this paper, we identify this new challenge, and present the first formal
and comprehensive model to enable rigorous investigations on this topic. We
propose a simple power management policy, and show that this policy achieves a
best possible notion of optimality. In fact, we show that the optimal power
consumption is attained in a "steady-state" operation and a simple policy of
finding and entering this steady state suffices, which can be quite surprising
considering the added complexity of this problem. Finally, we validated the
efficiency of our policy with experiments.

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