process-schedule

Question

Consider the 3 processes, P1, P2 and P3 shown in the table. Process Arrival time Time Units Required

 (arrival time,time required)

P1  0  5

P2  1  7

P3  3  4

 The completion order of the 3 processes under the policies FCFS and RR2 (round robin scheduling with CPU quantum of 2 time units) are

(A) FCFS: P1, P2, P3 RR2: P1, P2, P3

(B) FCFS: P1, P3, P2 RR2: P1, P3, P2

(C) FCFS: P1, P2, P3 RR2: P1, P3, P2

(D) FCFS: P1, P3, P2 RR2: P1, P2, P3

operating-system process-schedule normal in fcfs order of execution is P1 P2 P3 in

RR2 0-2 :p1   2-4:p2   4-6:p1   6-8:p3   8-10:p2   10-11:p1   11-13 :p3   13-15:p2   15-16:p2

p1completes at 11 P3 completes at 13 P2 at 16 so order is P1 P3 P2

can anyone give me proper explanation, i cant understand why in 4-6 part p1 is taking (not p3?).

Answer 1

not getting what you are asking but I hope the below work help you.