uC/OS-II

Hey all, Here is a collection of uC/OS-II questions that would be of great interest and that can be discussed !

1. Expansion of uC/OS-II ?
2. What is the footprint size of uC/OS-II ?
3. Roughly, how man lines of code is it ?
4. What type of scheduler is supported by uC/OS-II ?
5. Does uc/OS-II RTOS support nested interrupts ? To how many levels ?
6. What are the APIs that play a significant role in uC/OS-II initialization ?
7. Binary semaphore in uC/OS-II use priority cieling to address priority inversion - True/False ?
8. What is the exact context switch time in uC/OS-II RTOS ?
9. Does uC/OS-II RTOS support MMU ?
10. Is it possible to use uC/OS-II RTOS without MMU ?
11. What could be the best reason/scenario for selecting uC/OS-II RTOS ?
12. Which is the lowest prirority task in uC/OS-II RTOS ?
13. The idle task is always the lowest-priority task and can not be deleted or suspended by usertasks - True / False ?
14. The idle task consumes some of the processor resources - True / False ? How to reduce the resource usage ?
15. What are the various states of task in uC/OS-II RTOS ?
16. Explain Task Scheduling in uC/OS-II RTOS ?
17. Task-level scheduling and ISR-level scheduling are done by OS_Sched() and OSIntExit(), respectively - True/False ?
18. Task level scheduling invokes a software interrupt for context switches in uC/OS-II RTOS - True / False ?
19. Why are interrupts disabled while identifying the high-prirority ready task ?
20. Which API services Clock ticks ?
21. uC/OS-II RTOS lacks soft realtime support - True / False.
22. Does uC/OS-II RTOS support sempahore / Tell about OSSemPend and OSsemPost use ?
23. Tell about the use of mailbox in uC/OS=II RTOS ?
24. If there is already a message in the mailbox, then an error is returned, and also it is not overwritten - True/False
25. uC/OS-II does not automatically check for the status of stacks - True/False
26. What is the use of OSTaskStkCheck() ?
27. How will you port uC/OS-II RTOS ?
28. While porting, Where do you do the compiler specific data type and processor specific changes for porting uC/OS-II RTOS or What are the changes specific to OS_CPU.h ?
29. WHat is the use of HOOK functions / APIs ?
30. How can you identify the exten to which the CPU is busy ?
31. WHere do you do the interrupt related processor specific changes for porting uC/OS-II RTOS ? or What are the changes to be done in OS_CPU_A.ASM ?
32. Tell about Message Queues operation ?
33. What is the difference between Mailbox and Message queue in uC/OS-II RTOS ?
34. What are hooks ?

PS - uC/OS-III RTOS has got released in March 2009 . The above questions have been framed based on uC/OS-II RTOS only.

RTOS

RTOS has become very important as it is concerned with time critical events. Okay, let me list down few of the famous RTOS questions that can be discussed here.

1. What is priority inversion ?
2. What are the solutions for priority inversion ?
3. What is priority inheritance ?
4. What is priority ceiling ?
5. What is deadlock ?
6. What is the famous diners problem ?
7. What is mutex ?
8. What is spinlock ?
9. Where are spinlocks used ?
10. What do you mean by atomic operations ?
11. what is a semaphore ?
12. What are the types of semaphore ?
13. What is binary semaphore ?
14. What is a counting semaphore ?
15. What is message queue ?
16. What is the role of a scheduler ? How does it function ?
17. What is the difference between a normal OS and RTOS ?
18. What is preemption ?
19. What is preemptive multi-tasking/time-sharing ? What is its difference with co-operative multi-tasking/time-sharing ?
20. Threads are described as lightweight because switching between threads does not involve changing the memory context - True/False ?
21.What are the factors considered for a RTOS selection ?
22. What is the use of the method of temporarily masking / disabling interrupts ? When is it used ? What should be taken care while doing this method ?
23. Since, disabling/masking of interrupts can be done whent the critical section is ONLY SHORT,What method can be used if the critical section is longer than few source lines or if it involves few lengthy loopings ?
24. Difference between semaphores and disabling/masking of interrupts method ?
25. Binary semaphore is equivalent to Mutex - True/False. How ?
26. How can you avoid deadlocks incase of semaphore based designs ?
27. What is Message passing method ? What is its advantages ?
28. Tell about the design of Interrupt Handler and Scheduler in RTOS ?
29. What is interrupt latency ?
30. Even if we never enables interrupts in the code, the processor automatically disables them often during hardware access - True/False ? In this case how to reduce interrupt latency ?
31. When should we re-enable the interrupts in an ISR and why ?
32. How do you measure the latency of your system ?
33. What are First Level Interrupt handlers and Second level Interrupt handlers ?
34. What could be the typical design/implementation of FLIH and SLIH ?
35. Reentrant interrupt handlers might cause a stack overflow from multiple preemptions by the same interrupt vector - True / False ?
36. What kind of memory allocation procedure is good for embedded systems ?
37. Is there any RTOS that has non-preemptive scheduling ?
38. What is reentrant code ?
39. What is preemptive multitasking ?
40. What does timeslice refer to ?
41. If the time slice is too short then the scheduler will consume too much of processing time - True / False
42. What is I/O bound ? What is CPU bound ?
43. What is non-preemptive multitasking ?
44. CFS uses 'nanosecond' granularity accounting, the atomic units by which individual process share the CPU instead of previous notion of 'timeslice' - True/False .
45. When will you use binary semaphore ?
46. When will you choose busy-wait instead of context switch ?
47. What are the possible scenarios in which context switching of threads can occur ?
48. Can you use mutex/semaphore inside an ISR ?
49. Explain a scenari that could cause deadlock ? What is the best solution for a deadlock ?
50. Will the performance of your application improve if it has only a single thread and it is running on multiple cores of a processor ?
51. What will happen if there are more threads requesting for CPU resource such as time ?
52. What is Gang Scheduling and how is it useful ?
53. Can you sleep in interrupt handler ?
54. What is the main drawback for not considering Linux as realtime / RTOS ?
55. What is the drawback in using semaphore for synchronization ? How does spinlock help in overcoming it ?
56. What does a semaphore consist of ? and What does a spinlock consist of ?
57. Why spinlocks are useless in uniprocessor systems ?
58. What is timeslice ?
59. What is the difference between multiprogramming and multiprocessing ?
60. What is parallel programming ?
61. What are the types of IPC mechanisms ?
62. What are the types of synchronization problems and what are the resources that can cause such problems ?
63. What is data race ?
64. What is Indefinite Postponement / Indefinite blocking or starvation ?
65. What are the synchronization relationships that are present in a multithreaded or mulitprogramming applications ?
66. How Many Processes or Threads Are Enough for an application ?
67. Tell the advantages and disadvantages of Co-operative multitasking.
67. When should we use mutex and when should we use semaphore ?
68. How do you select a scheduler for your project
69. What are the types of approach for designing a scheduler
70.