GATE CSE 2023 CS Q38: Operating System

Consider the two functions inc and dec shown below.

inc(){ dec(){

wait(s); wait(s);

X = X+1; X = X-1;

signal(s); signal(s);

} }

There are 5 threads each invoking inc once, and 3 threads each invoking dec 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?

Your answerChoose one option.

15, 7

7, 7

12, 7

12, 8

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