Introduction to Operating Systems Nptel Week 6 Answers
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Introduction to Operating Systems Nptel Week 6 Answers
Introduction to Operating Systems Nptel Week 6 Answers (July-Dec 2024)
1. Which of the following are atomic statements?
i) if(count==0) ii) add %eax,%ebx
A) i is atomic, ii is non-atomic B) i is non-atomic, ii is non-atomic C) i is non-atomic, ii is atomic D) Both are atomic
Answer: C) i is non-atomic, ii is atomic
2. When a process exiting a critical section calls wakeup(), all the contending processes wake up at once. This is called and can be used to solve this problem. (Choose the option such that the first word is the answer for the first blank, and the second word is for the second blank)
A) Thundering herd problem, Process queue B) Lost wakeup, Process queue C) Thundering herd, Semaphores D) Lost wakeup, Semaphores
Answer: A) Thundering herd problem, Process queue
3. State True/False.
Peterson’s solution is a synchronization mechanism that works for a maximum of two processes.
A) True B) False
Answer: A) True
4. If the value of a counting semaphore s = 6, then the maximum number of requests for the critical section before it blocks is _?
A) 0 B) 2 C) 4 D) 6
Answer: D)6
5. Which of the following is not an atomic primitive?
A) Test and Set B) Test-test and set C) Cmp and swap D) None of the above
Answer: D) None of the above
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6. Consider the notation nP and mV to indicate n down operations and m up operations on a semaphore respectively. In a certain application, the initial value of a counting semaphore s is 15. The following operations were completed on the semaphore in the given order: 5P, 8P, 4V, 7P, 6V, 3P, 4V. The new value of the counting semaphore is _?
7. Consider the notation nP and mV to indicate n down operations and m up operations on a semaphore respectively. For an application using a counting semaphore, the following sequence of operations is obtained: 6P, 3V, 5P, 4V, 8P. The value of the semaphore at the end of these operations is -4. What is the initial value of the semaphore?
Answer: 8
8. State True or False.
If the current value of a counting semaphore s = -2, i.e., the number of processes that can enter the critical section is 2.
A) True B) False
Answer: B) False
9. Atomic operations like test and set ensure that:
A) They are executed in a single cycle. B) They can be executed in multiple cycles, no other memory instruction is executed while this instruction is executing. C) They can be executed in multiple cycles, but no other memory instruction to the same variable is executed while this instruction is executing. D) No other instructions execute in the background while this instruction is being executed.
Answer: C) They can be executed in multiple cycles, but no other memory instruction to the same variable is executed while this instruction is executing.
10. When the return value of fork() is zero, it indicates the current process is:
A) Parent process B) Child process C) Forking failed
Answer: B) Child process
These are Introduction to Operating Systems Nptel Week 6 Answers
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These are Introduction to Operating Systems NPTEL Assignment 6 Answers
Q1. Consider the following statements: i) if(count==0) ii) add %eax,%ebx i is atomic , ii is non-atomic i is non-atomic , ii is non-atomic i is non-atomic , ii is atomic Both are atomic
Q2. Which of the following condition could occur due to lack of synchronization? Inconsistency Loss of data Deadlock All of these
Answer: All of these
Q3. Return value of xchg instruction is_____________ Old value New value 1 if operation succeeds and 0 if operation fails None of the above
Answer: Old value
These are Introduction to Operating Systems NPTEL Assignment 6 Answers
Q4. By using intel hardware xchg instruction, ensures that The critical section is deadlock free Solution is starvation free Process enters CS in FIFO order More than one process enters critical section at same time Which of the above statement is TRUE? a only a and b b and c d only
Answer: a only
Q5. Your friend wants to design synchronization primitives and tells you that he would be better off by strictly ensuring that the processes alternate the critical section. Your response would be: That might not satisfy the “progress” requirement That might not satisfy the “mutual exclusion” requirement That might not satisfy the “bounded wait” requirement I guess that would suffice.
Answer: That might not satisfy the “progress” requirement
Q6. State True/False Bakery algorithm ensures that no process is starved. True False
Answer: True
These are Introduction to Operating Systems NPTEL Assignment 6 Answers
Q7. State True/ False Message passing is slow compared to shared memory and more error prone. True False
Answer: False
Q8. Inter process communication with message passing, the shared memory is in User space Kernel space Virtual memory None of these
Answer: Kernel space
Q9. In a certain application, the initial value of a counting semaphore s is 10. The following operations were completed on the semaphore in the given order 5P, 20P, 2V, 18P, 5V, 10P, 1V. The new value of counting semaphore is ______ ?
Answer: -35
These are Introduction to Operating Systems NPTEL Assignment 6 Answers
Q10. If the value of a counting semaphore s = 4, then the maximum number of requests for the critical section before it blocks is _____? 0 1 2 4
Q11. State True/False It is possible to share the messages even without attaching the shared memory with the address space of calling process. True False
Answer: False
Q12. The variable turn can have values 0 or 1
Void Process (i)
{
while(1)
{
//Non-critical section
While (turn!=i);
// Critical section
turn = j;
}
}
The above code does not provide Mutual exclusion Progress Bounded wait None of these
Answer: Progress
These are Introduction to Operating Systems NPTEL Assignment 6 Answers
Q13. Test and Set instruction, which provides hardware synchronization does not guarantee ________. Mutual exclusion Progress Bounded wait None of these
Answer: Bounded wait
Q14. Peterson’s solution is a synchronization mechanism for maximum of _____ processes.
Answer: 2
Q15. Atomic operations like test&set ensure that They are executed in a single cycle They can be executed in multiple cycles,no other memory instruction is executed while this instruction is executing They can be executed in multiple cycles,but no other memory instruction to the same variable is executed while this instruction is executing No other instructions execute in the background while this instruction is being executed
Answer: They can be executed in multiple cycles,but no other memory instruction to the same variable is executed while this instruction is executing
These are Introduction to Operating Systems NPTEL Assignment 6 Answers
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