SRM University 2007 B.Tech Information Technology IT204 / CS202 - OPERATING SYSTEMS - Question Paper

i.A 4th process arrives with maximum memory need of 60 and initial need of 25 units.
ii. A 4th process arrives with maximum memory need of 60 and initial need of 35 units.

3. a)Explain Peterson’s algorithm for solving mutual exclusion issue.
b)M processes share N resource units that can be reserved and released only 1 at a time.The maximum need of every process does not exceed M, and the sum of all the maximum needs is less than M+N.Show that a deadlock cannot occur.

4. a)How will you achieve mutual exclusion through hardware support.
b)What is a binary semaphore?Explain the algorithm for implementing
infinite buffer producer/consumer issue using binary semaphore.

5. a)Explain the use of semaphore for process co-ordination.
b)Is busy waiting always less efficient in terms of processor utilization than blocking wait?Explain.

6. a)Explain mutual exclusion using semaphore.
b)Apply deadlock detection algorithm to the subsequent and show the outcomes.
Available = two one 0 0

two 0 0 one 0 0 one 0
Request = one 0 one 0 Allocation = two 0 0 1
two one 0 0 0 one two 0

7. Clearly discuss with the help of an algorithm, how the infinite buffer producer/consumer issue may be solved using semaphore.

8. Clearly discuss with the help of an algorithm, how the finite buffer producer/consumer issue may be solved using semaphore.

10.Consider the subsequent snapshot of a system.There are no current outstanding
queued unsatisfied requests.
available
r1 r2 r3 r4
2 1 0 0


Current allocation maximum demand still needs
Process r1 r2 r3 r4 r1 r2 r3 r4 r1 r2 r3 r4
P1 0 0 1 2 0 0 1 2
P2 2 0 0 0 2 7 5 0
P3 0 0 3 4 6 6 5 6
P4 2 3 5 4 4 3 5 6
P5 0 3 3 2 0 6 5 2


a) calculate what every process still might request .
b) Is the system currently in safe or unsafe state ? Why?
c) Is the system currently deadlocked? Why or Why not?
d) Which processes, if any, are or may become deadlocked?
e) If a request for P3 arrives for (0,1,0,0) , can that request be safely granted immediately? In what state ( deadlocked, safe,unsafe) would immediately granting that whole request leave the system?Which processes, if any are or may become deadlocked if this whole request is granted immediately?

Earning:   Approval pending.