Question

Computer Operating Systems

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Please give answers for questions a-g with full sentences. Thank you in advance.

Answer 1

a.

FCFS à

CPU utilization is given by = (280-(45*cs)/ 280-(45*cs) + 2*cs)

Where cs is the context switching.

SJF à

CPU utilization is given by = (311- (45*cs)/ 311 – (45*cs) + 3*cs)

Where cs is the context switching.

Since both algorithm are executing the same processes cs is equal for them. Hence CPU utilization for FCFS is better.

b.  Contest switches (cs) for FCFS is equal to 8 since there as 9 different processes with each executed only once

c.  Contest switches (cs) for SJF is equal to 8 since there as 9 different processes with each executed only once.

d.  It is a process of storing the state of a process so that it can be restores or resumed again from the same point. Since it affects the CPU utilization using the before mentioned formula, it affects the performance of each algorithm

e. SJF algorithm has lowest Average Wait Time.

f.  FCFS algorithm has lowest Average Response Time

g.  SJF has the lowest Average Turnaround Time.