Real-Time Operating Systems: Determinism, Scheduling and OT Security
A real-time operating system is not a fast operating system. It is a predictable one. The guarantee an RTOS makes is that a task will complete within a known time bound, every time — and it will sacrifice average throughput to keep that promise. A general-purpose operating system optimizes for overall responsiveness and fairness. If a task is occasionally delayed by 50 milliseconds while the system does something else, nobody notices. In an airbag controller, an infusion pump or a protection relay, that delay is the failure. Hard, Firm and Soft Hard real-time — missing a deadline is a system failure, potentially a catastrophic one. Flight control, engine management, medical devices, industrial safety interlocks. Firm real-time — a missed deadline makes that result useless, but the system continues. A dropped frame in a video pipeline. Soft real-time — a missed deadline degrades quality. Audio playback, most user interfaces. The exam distinction is...