Which statement defines deterministic timing in a real-time system and describes a common approach to guarantee WCET?

Which statement defines deterministic timing in a real-time system and describes a common approach to guarantee WCET?

• A. Fixed bounds on timing.
• B. Fixed bounds on timing and WCET can be guaranteed via static analysis, bounded interrupts, and reserved CPU time.
• C. Timing is variable with workload.
• D. Timing is random.

Answer: (B)

Deterministic timing means the system’s response times are predictable and bounded, no matter what workload is running. To guarantee the worst-case execution time, you need a plan that enforces those bounds. Static analysis examines the code and hardware to compute an upper limit on how long a task could take in the worst case. Bounded interrupts prevent long, unpredictable delays by limiting how long interrupts can hold the CPU or by controlling when they can occur. Reserved CPU time ensures the task has guaranteed access to the processor when needed, so it won’t be delayed by other work. Together, these techniques establish a fixed, provable upper bound on execution time, which is essential for meeting deadlines in real-time systems. The other statements describe timing that can vary or be random, which isn’t deterministic.

Deterministic timing means the system’s response times are predictable and bounded, no matter what workload is running. To guarantee the worst-case execution time, you need a plan that enforces those bounds. Static analysis examines the code and hardware to compute an upper limit on how long a task could take in the worst case. Bounded interrupts prevent long, unpredictable delays by limiting how long interrupts can hold the CPU or by controlling when they can occur. Reserved CPU time ensures the task has guaranteed access to the processor when needed, so it won’t be delayed by other work. Together, these techniques establish a fixed, provable upper bound on execution time, which is essential for meeting deadlines in real-time systems. The other statements describe timing that can vary or be random, which isn’t deterministic.