GATE Overflow | Operating Systems | Test 1 | Question: 9

Question

Each process $P_i$, where $i= 1$ to $9$ is coded as follows  

repeat 
 P (mutex)
   {critical section }
 V (mutex)
 forever 

The code for $P_{10}$ is identical except that it uses $V$ (mutex) instead of $P$ (mutex) and vice-verse. What is the largest number of processes that can be inside the critical section at any moment if initial value of the semaphore is 1? 

• A. 1
• B. 2
• C. 3
• D. none

Comments

the correct answer should be 10

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@MiNiPanda

 

Here also repeat forever then why we cant use P10 more than one time ?

 

 

Answer 1

$P_1$ enters CS; preempt. mutex = 0 now.

$P_{10}$ enters CS; preempt. mutex = 1 now.

$P_2$ enters CS. mutex = 0 again.

That's it.

Option C