modified question

Question

Each Process Pi, i = 1....91....9 is coded as follows

while(TRUE)
{ 
    P(mutex)
    {Critical section}
    V(mutex)
}

The code for P10 is 

while (TRUE)
{ 
    v(mutex)
    {Critical section}
    p(mutex)
}

. What is the largest number of processes that can be inside the critical section at any moment?

1. 1
2. 2
3. 3
4. 10

Comments

if value of binary semaphore initially is 1 then 3 processes can enter into CS at max at a time

any process from $P_0$ to $P_9$ can enter and will make value 0

then process $P_{10}$ can enter and make value 1 again

then any other process can enter and make 0 again

Answer 1

Initially mutex = 1

Let ,

P1 enters by P operation---> mutex=0

P10 enters by V operation ---> mutex=1

P2 enters by P operation ---> mutex=0

This is the one case where 3 process are present in critical section