GATE | CSE 2023 | Question 39

Consider the two functions incr and decr shown below.

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

There are 5 threads each invoking incr once, and 3 threads each invoking decor 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, and V2 be the values of X at the end of the execution of all the threads with implementations I-1, and y

I-2, respectively.

Which one of the following choices corresponds to the minimum possible values of V1, V2, respectively?

(A)

(B)

(C)

(D)