1. What is a
Real-Time System?
2. Does the
RTOS give you a flexible set of scheduling policies?
3. Does the
RTOS use the dynamic object’s address as its identifier?
4. Are
interrupts handled with a macro/function or do you have to write your own
prologue (entry) and epilogue (exit)?
5. How does
the RTOS synchronize with events? Do your event synchronization objects
automatically clear with a task release or can events be missed? Can multiple
tasks wait on a single event? Can a single task wait on multiple events?
6. Does the
RTOS allow you to count both periodic or aperiodic ticks?
7. Can the
RTOS count ticks other than time?
8. Are
Timers/Alarms globally available so that they can be used by multiple tasks or
are they tied to a single task? Does the RTOS allow you to define future
actions to be taken when any counter reaches a predefined value?
9. Does the
RTOS manage RAM with a heap that can create non-deterministic response and
fragmentation?
10.Does the
RTOS provide multiple data passing options?
11. Does the
RTOS allow data to be passed between tasks and ISRs (or just between tasks)?
12. How does
the RTOS provide exclusive access to resources? Does it use binary semaphores
or mutexes?
13. Does the
RTOS have a mechanism to prevent priority inversion—when a low priority task
has control of a resource that is required by a higher priority task?
14. How the
RTOS is coded. Is it designed for deterministic operation? Does it ensure low
system overhead? Low latency? Responsive services?
15. Write a
code to connect Hardware interrupt to ISR?
16. What is
priority inversion ? and What is the solution ?
17. Explain
Priority Inheritance
18. Explain
various types of Scheduling
19. Which
RTOS supports Non-Preemptive scheduling ? Why other scheduling methods are
supported by such OSes?
20. RTOS vs
OS21. what is a non re-entrant code?
22. Is unix
a multitasking or multiprocessing operating system? whats the difference
between the two?
23. What is
stack overflow and heap overflow?
24. What is
a core dump?
25. Windows
also has multiple processes has process priotities switches between multiple
process, how RTOS is different from that?
26. what is
paging, segmentation Why do we need it?
27. write a
code to check wther a stack grows upwards or downwards?
28. Why do
we require semaphore mutex?
29. write a
small piece of code protecting a shared memory variable with a semaphore?
SOME MORE
RTOS QUESTIONS:
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 ?
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