Round Robin Scheduling

  • Each process is provided a fix time to execute called quantum.

  • Once a process is executed for given time period. Process is preempted and other process executes for given time period.

  • Context switching is used to save states of preempted processes.



Example:

Process Arrival Time Execute Time
P0 0 5
P1 1 3
P2 2 8
P3 3 6


P0

P1

P2

P3

P0

P2

P3

P2

0 3 6 9 12 15 18 21 24


Wait time of each process is following

ProcessWait Time : Service Time - Arrival Time
P0(0-0) + (12-3) = 9
P1(3-1) = 2
P26-2) + (15-9) = 10
P3(9-3) + (18-12) = 12

Average Wait Time: (9+2+10+12) / 4 = 8.25





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