General purpose operating systems (OS) are concurrent and multithread, and the primary goal of thread scheduler is to enforce fairness among all threads. This design is unsuitable for Real-Time (RT) systems, because tasks have soft or hard deadline of finishing time. Concurrency breaks timing of RT applications because users never know when their program is actually running. Explicitly allocation of processor resource to programs (threads) is thus necessary for timing-aware applications.
Central to the operation of cyber-physical systems (CPS) is accurate and reliable knowledge of time, both for meaningfully sensing and controlling the physical world state and for correct, high-performance and energy-efficient orchestration of computing and communication operations. Emerging applications that seek to control agile physical processes or depend on precise knowledge of time to infer location and coordinate communication, make use of time with diverse semantics and dynamic quality requirements.
