Doing some round robin scheduling math

1
votes

This is the question I faced and couldn't solve it:

Five processes with computation times: x, 5, 8, 6, 10 request entering at t=0.
Average waiting time is 20ms. Find X if we use FCFS, SJF, Round Robin (quantum=1ms)
I solved it with FCFS and SJf -> x is around 14
But how to solve with Round Robin?

Round Robin uses time slices and if we assume x > 10 (which seems to be) then the waiting time would be independent from the value of x.

1
schedulinground-robin

1 Answers

0
votes

if we have compute times as u say, the formula for finding out the average is

((5A + 4B + 3C + 2D + F)/5) = 20.

Reducing we get (5X + 20 + 24 + 12 + 10) = 100

Finally just a simple equation x = 34/5 ~ 7