5 / 15 Scheduling

Twenty Nine Versus One

Three CPU-bound jobs A, B and C all arrive at t=0t=0 and each needs 10 ms. Context switches are free.

  • FIFO runs A to completion, then B, then C.
  • Round robin uses a 1 ms quantum and cycles A, B, C.

Turnaround is Tcompletion−TarrivalT_{completion} - T_{arrival}; response is Tfirstrun−TarrivalT_{firstrun} - T_{arrival}.

What are round robin's average turnaround and FIFO's average response?

A

RR turnaround 30 ms, FIFO response 0 ms

B

RR turnaround 29 ms, FIFO response 10 ms

C

RR turnaround 20 ms, FIFO response 10 ms

D

RR turnaround 29 ms, FIFO response 1 ms