Operating System


Question 1
Consider a computer system with 57-bit virtual addressing using multi-level tree-structured page tables with L levels for virtual to physical address translation. The page size is 4 KB (1 KB = 1024 B) and a page table entry at any of the levels occupies 8 bytes.
The value of L is ______.
A
4
B
5
C
6
D
7
GATE CSE 2023      Memory Management
Question 2
Consider the following two-dimensional array D in the C programming language, which is stored in row-major order:

int D[128][128];

Demand paging is used for allocating memory and each physical page frame holds 512 elements of the array D. The Least Recently Used (LRU) page-replacement policy is used by the operating system. A total of 30 physical page frames are allocated to a process which executes the following code snippet:

for (int i = 0; i < 128; i++)
       for (int j = 0; j < 128; j++) 
                   D[j][i] *= 10;

The number of page faults generated during the execution of this code snippet is _____.
A
128
B
4096
C
1024
D
2048
GATE CSE 2023      Memory Management


Question 3
Consider the two functions incr and decr shown below.

incr(){
  wait(s);
  X = X+1;
  signal(s);
}

decr(){
  wait(s);
  X = X-1;
  signal(s);
}

There are 5 threads each invoking incr once, and 3 threads each invoking decr once, on the same shared variable X. The initial value of X is 10.
Suppose there are two implementations of the semaphore s, as follows:

I-1: s is a binary semaphore initialized to 1.
I-2: s is a counting semaphore initialized to 2.

Let V1, V2 be the values of X at the end of execution of all the threads with implementations I-1, I-2, respectively.
Which one of the following choices corresponds to the minimum possible values of V1, V2, respectively?
A
15, 7
B
7, 7
C
12, 7
D
12, 8
GATE CSE 2023      Process Synchronization
Question 4
Which one or more of the following CPU scheduling algorithms can potentially cause starvation?
A
First-in First-Out
B
Round Robin
C
Priority Scheduling
D
Shortest Job First
GATE CSE 2023      CPU Scheduling
Question 5
Which one or more of the following options guarantee that a computer system will transition from user mode to kernel mode?
A
Function Call
B
malloc Call
C
Page Fault
D
System Call
GATE CSE 2023      System Call




There are 5 questions to complete.

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