Operating System Multiple choice Questions and Answers-CPU Scheduling

1.	Using Priority Scheduling algorithm, find the average waiting time for the following set of processes given with their priorities in the order: Process : Burst Time : Priority respectively . P1 : 10 : 3 , P2 : 1 : 1 , P3 : 2 : 4 , P4 : 1 : 5 , P5 : 5 : 2.
a.	8 milliseconds
b.	8.2 milliseconds
c.	7.75 milliseconds
d.	3 milliseconds

Discuss

Answer: (b).8.2 milliseconds

2.	A major problem with priority scheduling is _________.
a.	Definite blocking
b.	Starvation
c.	Low priority
d.	None of the above

Discuss

Answer: (b).Starvation

3.	The host repeatedly checks if the controller is busy until it is not. It is in a loop that status register's busy bit becomes clear. This is called _____________ and a mechanism for the hardware controller to notify the CPU that it is ready is called ___________.
a.	Interrupt and Polling
b.	Polling and Spooling
c.	Polling and Interrupt
d.	Deadlock and Starvation

Discuss

Answer: (c).Polling and Interrupt

4.	An optimal scheduling algorithm in terms of minimizing the average waiting time of a given set of processes is ________.
a.	FCFS scheduling algorithm
b.	Round robin scheduling algorithm
c.	Shorest job - first scheduling algorithm
d.	None of the above

Discuss

Answer: (c).Shorest job - first scheduling algorithm

5.	In Priority Scheduling a priority number (integer) is associated with each process. The CPU is allocated to the process with the highest priority (smallest integer = highest priority). The problem of Starvation of low priority processes may never execute, is resolved by __________.
a.	Terminating the process
b.	Aging
c.	Mutual Exclusion
d.	Semaphore

Discuss

Answer: (b).Aging

6.	CPU performance is measured through ________.
a.	Throughput
b.	MHz
c.	Flaps
d.	None of the above

Discuss

Answer: (a).Throughput

7.	With the round robin CPU scheduling in a time-shared system ________.
a.	Using very large time slice degenerates in to first come first served algorithm
b.	Using extremely small time slices improve performance
c.	Using extremely small time slices degenerate in to last in first out algorithm
d.	Using medium sized time slices leads to shortest request time first algorithm

Discuss

Answer: (a).Using very large time slice degenerates in to first come first served algorithm

8.	Which of the following is a criterion to evaluate a scheduling algorithm?
a.	CPU Utilization: Keep CPU utilization as high as possible
b.	Throughput: number of processes completed per unit time
c.	Waiting Time: Amount of time spent ready to run but not running
d.	All of the above

Discuss

Answer: (d).All of the above

9.	_________ does the job of allocating a process to the processor.
a.	Long term scheduler
b.	Short term scheduler
c.	Medium term scheduler
d.	Dispatcher

Discuss

Answer: (d).Dispatcher

10.	In interactive environments such as time-sharing systems, the primary requirement is to provide reasonably good response time and in general, to share system resources equitably. In such situations, the scheduling algorithm that is most popularly applied is ________.
a.	Shortest Remaining Time Next (SRTN) Scheduling
b.	Priority Based Preemptive Scheduling
c.	Round Robin Scheduling
d.	None of the above

Discuss

Answer: (c).Round Robin Scheduling