RTOS and concurrency: interview prep

Interview questions

Key points for each answer are in the app's question bank.

1. Describe the task states in a typical RTOS.Basic
2. Preemptive versus cooperative scheduling: trade-offs?Basic
3. Mutex versus binary semaphore versus counting semaphore.Basic
4. What is priority inversion? Explain two ways to prevent it.Intermediate
5. What conditions lead to deadlock, and how do you prevent it?Intermediate
6. Show a race condition between a task and an ISR, and fix it.Basic
7. How does a context switch work on Cortex-M?Advanced
8. When would you use a queue, a task notification or an event group?Intermediate
9. How do you size task stacks and detect stack overflow?Intermediate
10. Why shouldn't an ISR call blocking RTOS APIs? How do you defer work?Basic
11. What is tickless idle and why does it matter?Intermediate
12. vTaskDelay versus vTaskDelayUntil: when do you need each?Basic
13. What is rate monotonic scheduling, and how do you check schedulability?Advanced
14. Compare ways to protect a critical section.Intermediate
15. What's the difference between reentrant and thread-safe functions?Intermediate
16. Compare FreeRTOS heap schemes heap_1 to heap_5.Intermediate
17. Design watchdog supervision for a system with six tasks.Advanced
18. Design a producer-consumer pipeline between an ISR and a task.Intermediate
19. How do Zephyr and FreeRTOS differ for a product team?Intermediate
20. How do RTOS software timers work, and what are their limits?Intermediate

Hands-on challenges

Design rounds

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