Interrupt Service Routine Design Questions

Design and implement deterministic, low latency interrupt service routines that correctly handle hardware events without jeopardizing system responsiveness or safety. Candidates should discuss principles for keeping handlers lean, bounding worst case execution time, deferring expensive work to task level or deferred processing, and minimizing stack and memory usage in interrupt context. Explain safe communication patterns between interrupt context and application code including atomic operations, memory barriers, lock free queues, short critical sections with interrupts disabled briefly, and signaling mechanisms. Cover interrupt priorities, nesting, latency analysis, interactions with direct memory access, and handling priority inversion and reentrancy. Include testing and validation approaches such as measuring interrupt latency and worst case execution time on target hardware, instrumentation techniques, and static analysis as well as trade offs between determinism, throughput, and maintainability.