Introduction to Operating Systems Nptel Week 3 Answers
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Introduction to Operating Systems Nptel Week 3 Answers
Introduction to Operating Systems Nptel Week 3 Answers (July-Dec 2024)
Q1.If the MAX_SIZE is 0x20000000, the virtual address of a kernel variable is 0x2fffffff, and the Physical memory starts from 0x00000000, then the Physical address of the kernel variable will be _. 0xffffffff 0x00ffffff 0x0fffffff 0xffffff
Answer: 0x0fffffff
Q2.The kernel pages in Physical and Virtual Address space are mapped randomly. True False
These are Introduction to Operating Systems Nptel Week 3 Answers
Q3.There are multiple copies of kernel in the Physical Address space but there is only one copy of kernel in Virtual Address space from where all the processes share it. True False
Answer: False
Q4.There are two processes currently in a system. Process A has no I/O operations, process B has an I/O operation that reads the input from the keyboard. When Process A pre-empts process B (not executing I/O) process B goes from to _. Ready, Running Ready, Runnable Running, Ready Blocked, Runnable
These are Introduction to Operating Systems Nptel Week 3 Answers
Q5There are two processes currently in a system. Process A has no I/O operations, process B has an I/O operation that reads input from the keyboard. When Process B executes the I/O, and Process A goes from to _. Running, Ready Ready, Runnable Ready. Running Blocked, Runnable
Answer: Ready. Running
Q6.When a child is being created from a parent using the fork() system call initially the state of the process is set to READY state and before the fork() system call returns the state is changed to RUNNING. True False
These are Introduction to Operating Systems Nptel Week 3 Answers
Q7.When a child process is created using the fork() system call, its state is set to running. True False
Answer: False
Q8.A zombie process is used to remove the reaper processes created on termination, which if not controlled, might lead to infinite resource leakage. True False
These are Introduction to Operating Systems Nptel Week 3 Answers
Q9.I. The value of all the registers are same for parent and child process except for the registers %eip and %ebp II. forkret changes only the %eip of child I- False, II- True I- False, II- False I- True, II – True I- True, II – False
Answer: I- False, II- True
Q10. -s flag of the readelf utility shows details about ___. Syntax errors Symbol table Semantics Headers
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q1. Match the following a. Inode 1) The pid is assigned to a process b. New state 2)Never exits c. Trapframe 3)Stores metadata d. init 4) For restarting a process after a context switch a-4, b-2, c-3, d-1 a-3, b-4, c-2, d-1 a-4, b-1, c-2, d-3 a-3, b-1, c-4, d-2
Answer: a-3, b-1, c-4, d-2
Q2. We have n number of fork system calls, denoted as nXfork(). What is the total number of process created? n 2^n 2^(n-1) (2^n) – 1
Answer: 2^n
Q3. State True/ False The process whose parent exited before the child is an orphan process. Can a process can be Zombie and Orphan at the same time. True False
Answer: False
These are Introduction to Operating Systems NPTEL Week 3Assignment Answers
Q4. What is the output of the following program for any value of a u =x+5 x=u+5 x=u+10 u=x+10
Answer: u =x+5
Q5. Which of the below statement is false. Init is the first process created using booting Init process is a daemon process. Init process have process identifier as 1 None of these
Answer: None of these
Q6. A student have written a program and used pid = fork() function call in it. The pid returned by the fork was 5119. Which of the following is true about the process invoking fork? Process is a parent process with pid = 5119 Process is a child process. Its Parent’s pid is 5119 The process is a parent process. Its Child’s pid is 5119 Process is a child process with pid = 5119
Answer: The process is a parent process. Its Child’s pid is 5119
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q7. Which of the following is false? Process : Contains code+data+heap+stack+process state Program : One program can be used to create many processes Process : Process is not a unique isolated entity Program : Code + Static and Global data
Answer: Process : Process is not a unique isolated entity
Q8. The state transition that occurs due to the scanf system call in the program is ______. NEW -> READY READY -> RUNNING RUNNING -> BLOCKED BLOCKED -> READY
Answer: RUNNING -> BLOCKED
Q9. Which one of the following is the property of Operating system that helps to prevent attacks? i)Rings ii) a separate stack for the kernel iii)Virtual memory iv) Shared Libraries i i, ii i, ii, iii i, ii, iii, iv
Answer: i, ii
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q10. State True or False. 1. If the parent and the child process share the same page table. Does this mean they share the same page frames in the RAM? 2. COW creates a copy of the shared pages if it changes. All further changes are made in this new page. True, False False, True False, False True, True
Answer: True, True
Q11. Match the following a. Init.d 1) Created when system call occurs b. Zombie 2) The %eax register is cleared when this is created c. Child process 3) Created by kernel while booting d. Trapframe 4) Allows a parent process to read the status of child a-1, b-2, c-3, d-4 a-3, b-4, c-2, d-1 a-2, b-1, c-4, d-3 a-4, b-3, c-1, d-2
Answer: a-3, b-4, c-2, d-1
Q12. State True/False In memory mapping, the entire kernel is mapped into process’ address space, which helps the user process to easily access the kernel data. True False
Answer: False
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q13. Arrange the following in order a. Change state to runnable b. Copy page directory contents from parent to child process c. Copy the trapframe from the parent process d. Change state to embryo a, c, b, d c, d, a, b d, b, c, a a, c, b, d
Answer: d, b, c, a
Q14. wait() system call inside the parent process returns the status of the child. What does it returns when it is called inside the child? Returns -1 , when it is not the parent of any other process Returns its own process id Returns the exit status of the parent currently exited. None of these.
Answer: Returns -1 , when it is not the parent of any other process
Q15. State True/False execlp() system call replaces the child process with a new program file, but the process ID will not change. True False
Answer: True
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
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These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q2) State True or False.
A program to compute the sum of first 5,000 numbers can be divided into 4 sub parts and executed on 4 CPUs using either fork or threads. The reason why we prefer fork is because large portions of the data/code between the 4 sub-parts are very similar and need not be duplicated.
a. True
b.False
Answer: a. True
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q3) Match the following :
1.NEW A. Waiting for an i/o
2.READY B. Currently Executing
3.RUNNING C. Process is being created
4.SLEEPING D. waiting to be picked up by scheduler
a. 1-A, 2-D, 3-B, 4-C
b. 1-C, 2-B, 3-D, 4-A
c. 1-A, 2-C, 3-D, 4-B
d. 1-C, 2-D, 3-B, 4-A
Answer: d. 1-C, 2-D, 3-B, 4-A
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q4) State True or False for a process currently in RUNNING state. A software interrupt will result in the change to ring 1.
a. True
b. False
Answer: b. False
Q5) State True or False. In the absence of system calls, a user process can never dynamically allocate memory.
a. True
b. False
Answer: a. True
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q6) The wait() system call inside the parent process returns the pid of an exiting child process. Which of the following best fits when wait is called inside the child process?
a. Returns -1, when the child is not the parent of any other process
b. Returns its own process id.
c. Returns the exit status of the parent currently exited.
d. Such a call is not feasible and is likely to crash the process.
Answer: a. Returns -1, when the child is not the parent of any other process
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q7) A student has written a program and used pid = fork() function call in it. The pid returned by the fork was 5129. Which of the following is true about the process invoking fork?
a. Process is a parent process with pid=5129
b. Process is a child process. Its Parent’s pid is 5129
c. The process is a parent process. Its Child’s pid is 5129
d. Process is a child process with pid = 5129
Answer: c. The process is a parent process. Its Child’s pid is 5129
Q8) State True/False
When the child process state is set to Zombie, all page directories and the kernel are also deallocated.
a. True
b. False
Answer: b. False
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q9) Which of the below statement is False.
a. Kernel stack can be used to store the context of a process.
b. User stack is used to store the function details during function calls.
c. Kernel stack is used to store the function arguments during systems calls.
d. Context of the process is useful to restart the process after some time.
Answer: d. Context of the process is useful to restart the process after some time.
These are Introduction to Operating Systems NPTEL Week 3 Assignment Answers
Q10) What is the output in the parent process? int main() { int a=0, pid; pid = fork(); if(pid == 0){ a= a – 10; printf(“u = %d\n”, a); } else{ a= a + 10; printf(“x = %d\n”,a); } }
