Module1: OS

Throughput is

• Total number of instructions executed at any point of time

• Number of instructions executed in unit of time

• Number of instructions executed in 10 unit of time

• None of the above

Which of the following is responsible for CPU scheduling?

• Long term scheduler

• Mid term scheduler

• Short term scheduler

• None of the above

CPU Scheduling is applied in

• Running state

• Waiting state

• Ready state

• New state

To increase the priority of the processes to avoid the problem of starvation which of the following is used.

• Aging

• Paging

• Segmentation

• Fragmentation

Consider five processes P1, P2, P3, P4, and P5 with their respective arrival time 0, 1, 2, 3, 4 and burst time 4, 3, 1, 2, 5. The average TAT for FCFS algorithm is

• 5.6

• 3.4

• 3.8

• 6.8

Consider three CPU-intensive processes, which require 10, 20 and 30 time units and arrive at times 0, 2 and 6, respectively. How many context switches are needed if the operating system implements a shortest remaining time first scheduling algorithm? Do not count the context switches at time zero and at the end.

• 4

• 3

• 2

• 1

An operating system uses shortest remaining time first scheduling algorithm for pre-emptive scheduling of processes. Consider the following set of processes with their arrival times and CPU burst times (in milliseconds):

Process Arrival Time Burst Time

P1 0 12

P2 2 4

P3 3 6

P4 8 5

The average waiting time (in milliseconds) of the processes is _________.

• 4.5

• 5.5

• 6.8

• 7.5

Consider the following set of processes, with the arrival times and the CPU-burst times given in milliseconds

Process Arrival Time Burst Time

P1 0 5

P2 1 3

P3 2 3

P4 4 1

What is the average turnaround time for these processes with the preemptive shortest remaining processing time first (SRPT) algorithm ?

• 5.8

• 7.75

• 6.5

• 5.50

Which of the following scheduling algorithms is non-preemptive?

• Round Robin

• Multilevel Queue Scheduling with Feedback

• FCFS

• SRTF

The maximum number of processes that can be in Ready state for a computer system with n CPUs is

• n

• n²

• 2n

• Independent of n