CS330 Chapter 6 Exam

Section 1: Multiple Choice Questions (20 Marks)

Question 1 Past Exam 2 Marks

What is the primary purpose of Peterson's solution in the context of process synchronization?

a) To optimize the performance of parallel algorithms b) To prevent deadlock in interprocess communication c) To prevent deadlock in more than two concurrent processes d) To ensure the orderly execution of processes in their critical sections

Question 2 Past Exam 2 Marks

How are counting semaphores utilized to control resource access?

a) By setting the semaphore value to the number of available resources b) By initializing the semaphore to 1 c) By performing a wait() operation to increment the count d) By performing a signal() operation to decrement the count

Question 3 Past Exam 2 Marks

How can we prevent deadlock in the Dining Philosophers problem using semaphores?

a) By allowing philosophers to pick up any two forks simultaneously b) By limiting the number of philosophers in the dining room at any given time c) By using semaphores and carefully managing the order in which philosophers can pick up forks d) By ensuring their philosophers always wait for a signal before picking up any forks

Question 4 Past Exam 2 Marks

How can race conditions be mitigated in an operating system?

a) By avoiding the use of shared resources altogether b) By introducing priority scheduling for processes c) By increasing the overall system clock speed d) By implementing mutual exclusion mechanisms such as locks or semaphores

Question 5 Past Exam 2 Marks

What is a semaphore in operating systems?

a) A variable or abstract data type used to control access to a common resource b) A process scheduling algorithm c) A type of hardware interrupt d) A type of memory management scheme

Question 6 Past Exam 2 Marks

Which condition must be met for deadlock to occur?

a) Mutual exclusion, hold and wait, no preemption, circular wait b) Mutual exclusion only c) Circular wait only d) No preemption only

Question 7 Past Exam 2 Marks

What does a semaphore initialized to 1 typically represent?

a) A mutex lock b) A counting semaphore c) A deadlock state d) An unlocked state

Question 8 Past Exam 2 Marks

What is mutual exclusion?

a) Allowing multiple processes to access a resource simultaneously b) Ensuring only one process accesses a critical section at a time c) Fair CPU allocation d) Avoiding deadlocks

Question 9 Past Exam 2 Marks

Which is NOT a condition necessary for deadlock?

a) Mutual exclusion b) Circular wait c) Resource preemption d) Hold and wait

Question 10 Past Exam 2 Marks

In the context of process synchronization, what is busy waiting?

a) Waiting by continuously checking a condition without releasing CPU b) Waiting by blocking the process c) Waiting with a timeout d) Waiting by yielding the CPU

Section 2: Short Answer Questions (18 Marks)

Question 11 Past Exam 4 Marks

What does it mean for a solution to the critical section problem to satisfy the condition of mutual exclusion for two processes P1 and P2? Also, explain why disabling interrupts cannot be a general solution to the critical section problem (give two reasons).

Question 12 Past Exam 5 Marks

What is the producer-consumer problem? Describe how semaphores can be used to solve this problem. Include the semaphores needed and their initial values.

Question 13 5 Marks

Explain the three requirements that any solution to the critical section problem must satisfy: Mutual Exclusion, Progress, and Bounded Waiting.

Question 14 4 Marks

What is a monitor in concurrent programming? How does it differ from semaphores in terms of ease of use and error prevention?

Section 3: Code Analysis (12 Marks)

Question 15 Past Exam 12 Marks

Consider two processes P1 and P2 executing concurrently and sharing a semaphore S, which is initialized to 0. The semaphore operations in the processes appear as shown below:

Process P1          Process P2
-                   -
-                   -
S1                  S2
wait(S)             signal(S)
-                   -
-                   -

a) Which one of the following is true? (4 marks)

(i) S1 and S2 will execute in any order
(ii) S1 will always execute before S2
(iii) S1 will always execute after S2
(iv) P1 and P2 will be deadlocked

b) Explain your answer with reasoning. (4 marks)

c) What would happen if S was initialized to 1 instead of 0? (4 marks)

🔒 CS330: Operating Systems