Page 124 - DCAP403_Operating System

Unit 6: Process Synchronization

6.10 Self Assessment Notes

Fill in the blanks:

1. .......................... involves the orderly sharing of system resources by processes.
2. .......................... are used in software systems in much the same way as they are in railway
systems.

3. Part of the program where the shared memory is accessed is called the .......................... .
4. A .......................... is a software synchronization tool with high-level of abstraction that
provides a convenient and effective mechanism for process synchronization.
5. Resource Allocation Graphs (RAGs) are .......................... labeled graphs.

6. Algorithms that avoid mutual exclusion are called .......................... synchronization
algorithms.
7. .......................... abstracted the key notion of mutual exclusion in his concepts of
semaphores.
8. “No preemption” condition also known as .......................... .

9. .......................... processes share a common, fixed-size (bounded) buffer.
10. Binary Semaphores can assume only the value 0 or the value .......................... .

6.11 Review Questions

1. What is a safe state? What is its use in deadlock avoidance?
2. Describe briefly any one method of deadlock prevention.

3. What is concurrency? Explain with example deadlock and starvation.
4. Explain the different deadlock strategies.

5. Can a process be allowed to request multiple resources simultaneously in a system where
deadlock are avoided? Discuss why or why not.
6. How deadlock situation are avoided and prevented so that no systems are locked by
deadlock?
7. Consider the following resource allocation situation:
Process P = {P1, P2, P3, P4, P5}
Resources R = {R1, R2, R3}

Allocation E = {P1®R1, P1®R2, P2®R2, P3®R2, P4®R3, P5®R2, R2®P4, R3®P1}
Resource instances n(R1)=3, n(R2)=4, n(R3)=1
Draw the precedence graph. Determine whether there is a deadlock in the above
situation.
8. Explain process synchronization process.
9. What do you mean by mutual exclusion conditions? Explain
10. Write short note on semaphore.

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