How to calculate average waiting time of Round robin scheduling?

process scheduling gantt-chart
JAN picture JAN · Jul 25, 2012 · Viewed 80.4k times · Source

Given this table : enter image description here

Those are the time lines (time slice = 4) : 

|p1|p1|p2|p3|p4|p5|p1|p2|p3|p4|p5|p2|p3|p4|p5|p2|p3|p4|p5|p2|p3|p3|
0  4  8 12 16  20 24 28 32 36 40 44 48 52 56 60 64 68 69 72 75 79 80

Is there a simple way to calculate the average waiting time ?

Thanks

Note: that there are several finish times for each process !

Note2 : This question also involved priority algorithm as a side exercise , please disregard the priority column for the Round robin algorithm

Answer

user3919801 picture user3919801 · Sep 8, 2014

You can calculate Waiting time by drawing Gantt chart so waiting time of ith process is equal to Completion time - (Arrival time + Burst time ) .

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