IBPS IT SO-Operating system-CPU Scheduling Algorithms-1

CPU Scheduling Algorithms-1

1) Round robin scheduling falls under the category of :
a) Non preemptive scheduling
b) Preemptive scheduling
c) None of these

Answer: b
Explanation: None.

2) With round robin scheduling algorithm in a time shared system,
a) using very large time slices converts it into First come First served scheduling algorithm
b) using very small time slices converts it into First come First served scheduling algorithm
c) using extremely small time slices increases performance
d) using very small time slices converts it into Shortest Job First algorithm

Answer: a
Explanation: All the processes will be able to get completed.

3) The portion of the process scheduler in an operating system that dispatches processes is concerned with :
a) assigning ready processes to CPU
b) assigning ready processes to waiting queue
c) assigning running processes to blocked queue
d) All of these

Answer: a
Explanation: None.

4) Complex scheduling algorithms :
a) are very appropriate for very large computers
b) use minimal resources
c) use many resources
d) All of these

Answer: a
Explanation: Large computers are overloaded with greater number of processes.

5) The FIFO algorithm :
a) first executes the job that came in last in the queue
b) first executes the job that came in first in the queue
c) first executes the job that needs minimal processor
d) first executes the job that has maximum processor needs

Answer: b
Explanation: None.

6) The strategy of making processes that are logically runnable to be temporarily suspended is called :
a) Non preemptive scheduling
b) Preemptive scheduling
c) Shortest job first
d) First come First served

Answer: b
Explanation: None.

7) Scheduling is :
a) allowing a job to use the processor
b) making proper use of processor
c) Both a and b
d) None of these

Answer: c
Explanation: None.

8) There are 10 different processes running on a workstation. Idle processes are waiting for an input event in the input queue. Busy processes are scheduled with the Round-Robin timesharing method. Which out of the following quantum times is the best value for small response times, if the processes have a short runtime, e.g. less than 10ms ?
a) tQ = 15ms
b) tQ = 40ms
c) tQ = 45ms
d) tQ = 50ms

Answer: a
Explanation: None.

9) Orders are processed in the sequence they arrive if _______ rule sequences the jobs.
a) earliest due date
b) slack time remaining
c) first come, first served
d) critical ratio

Answer: c
Explanation: None.

10) Which of the following algorithms tends to minimize the process flow time ?
a) First come First served
b) Shortest Job First
c) Earliest Deadline First
d) Longest Job First

Answer: b
Explanation: None.

11) Under multiprogramming, turnaround time for short jobs is usually ________ and that for long jobs is slightly ___________.
a) Lengthened; Shortened
b) Shortened; Lengthened
c) Shortened; Shortened
d) Shortened; Unchanged

Answer: b
Explanation: None.

12) Which of the following statements are true ? (GATE 2010)
I. Shortest remaining time first scheduling may cause starvation
II. Preemptive scheduling may cause starvation
III. Round robin is better than FCFS in terms of response time
a) I only
b) I and III only
c) II and III only
d) I, II and III

Answer: d
Explanation:
I) Shortest remaining time first scheduling is a preemptive version of shortest job scheduling. It may cause starvation as shorter processes may keep coming and a long CPU burst process never gets CPU.
II) Preemption may cause starvation. If priority based scheduling with preemption is used, then a low priority process may never get CPU.
III) Round Robin Scheduling improves response time as all processes get CPU after a specified time.