ISRO CS 2017

Question 51

Consider three CPU intensive processes, which require 10, 20, 30 units and arrive at times 0, 2, 6 respectively. How many context switches are needed if shortest remaining time first is implemented? Context switch at 0 is included but context switch at end is ignored

• 1
• 2
• 3
• 4

Question 52

A process executes the following code

for (i = 0; i < n; i++) fork( ); 

The total number of child processes created are

• n²
• 2ⁿ⁺¹ -1
• 2ⁿ
• 2ⁿ -1

Question 53

Consider the following scheduling

A. Gang scheduling	s. Guaranteed scheduling
B. Rate Monotonic scheduling	t. Thread scheduling
C. Fair share scheduling	u. Real time scheduling

Matching the table in the order A, B, C gives

• t, u, s
• s, t, u
• u, s, t
• u, t, s

Question 54

A system uses FIFO policy for page replacement. It has 4 page frames with no pages loaded to begin with. The system first accesses 50 distinct pages in some order and then accesses the same 50 pages in reverse order. How many page faults will occur?

• 96
• 100
• 97
• 92

Question 55

Which of the following is false?

• User level threads are not scheduled by the kernel
• Context switching between user level threads is faster than context switching between kernel level threads
• When a user thread is blocked all other threads of its processes are blocked
• Kernel level threads cannot utilize multiprocessor systems by splitting threads on different processors or cores

Question 56

Which one of the following are essential features of object oriented language? A. Abstraction and encapsulation B. Strictly-typed C. Type-safe property coupled with sub-type rule D. Polymorphism in the presence of inheritance

• A and B only

• A, D and B only

• A and D only

• A, C and D only

Question 57

Which languages necessarily need heap allocation in the run time environment?

• Those that support recursion

• Those that use dynamic scoping

• Those that use global variables

• Those that allow dynamic data structures

Question 58

Consider the code segment

int i, j, x, y, m, n;
 n=20;
 for (i = 0, i < n; i++)
  {
    for (j = 0; j < n; j++)
     {
        if (i % 2)
        {
         x + = ((4*j) + 5*i);
         y += (7 + 4*j);
        }
     }
  }
  m = x + y;

Which one of the following is false

• The code contains loop invariant computation

• There is scope of common sub-expression elimination in this code

• There is scope of strength reduction in this code

• There is scope of dead code elimination in this code

Question 59

Consider the following table

A. Activation record	p. Linking loader
B. Location counter	q. Garbage collection
C. Reference counts	r. Subroutine call
D. Address relocation	s. Assembler

Matching A, B, C, D in the same order gives :

• p, q, r, s
• q, r, s, p
• r, s, q, p
• r, s, p, q

Question 60

Consider a disk sequence with 100 cylinders. The request to access the cylinder occur in the following sequence : 4, 34, 10, 7, 19, 73, 2, 15, 6, 20 Assuming that the head is currently at cylinder 50, what is the time taken to satisfy all requests if it takes 2 ms to move from one cylinder to adjacent one and shortest seek time first policy is used?

• 190
• 238
• 233
• 276