Question 8713 – CPU-scheduling

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):

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

Correct Answer: A

WT – Waiting Time
CT – Completion Time
TAT – Turn Around Time
TAT = CT – AT < br>
WT = TAT – BT
Gantt chart using Shortest remaining time first,

Avg. WT = 15+0+3+4/4 = 22/4 = 5.5