GATE CS 2025 Set 1 — Question 29
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Operating System → Processes & Threads → Context Switching
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Question
Suppose in a multiprogramming environment, the following C program segment is executed. A process goes into I/O queue whenever an I/O related operation is performed. Assume that there will always be a context switch whenever a process requests for an I/O, and also whenever the process returns from an I/O. The number of times the process will enter the ready queue during its lifetime (not counting the time the process enters the ready queue when it is run initially) is _______. (Answer in integer)
int main()
{
int x=0,i=0;
scanf("%d", &x);
for(i=0; i<20; i++)
{
x = x+20;
printf("%d\n",x);
}
return 0;
}
Correct answer
21 to 21
Solution
The process enters the ready queue whenever it returns from an I/O operation. In the given C program:
1.
scanf("%d",&x); is an I/O operation. When the I/O request is made, the process moves to the I/O queue. Upon completion of the I/O, it enters the ready queue. This happens 1 time.2.The
for loop executes 20 times (for ).3.Inside the loop,
Total number of times the process enters the ready queue = .printf("%d\n",x); is an I/O operation. Each time it is called, the process moves to the I/O queue and then enters the ready queue upon completion. Since the loop runs 20 times, this results in 20 entries into the ready queue.Continue learning with Success Tracker
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