In multilevel queue scheduling , if one level time quantum exits, it goes to next lower level
ML Queue Scheduling uses RR scheduling
Here it is given time quantum of 1st level queue is 2 ms
2nd level of queue is 4 ms
and 3rd level queue is 8 ms
Now, solve accordingly
$P_{1}$ |
$P_{2}$ |
$P_{3}$ |
$P_{1}$ |
$P_{2}$ |
$P_{4}$ |
$P_{5}$ |
$P_{4}$ |
$P_{5}$ |
$P_{2}$ |
$0.$ $2$ $4$. $6$. $8$. $12$ $14$. $16$. $20$. $23$. $25$
$\underbrace{.{\color{Magenta}{1st- level-queue } } }$$\underbrace{.{\color{blue}{2nd-- level } } }$$\underbrace{.{\color{Magenta}{1st-- level } } }$$\underbrace{.{\color{blue}{2nd-level } } }$$\underbrace{.{\color{red}{3rd- level } } }$
Now, Throughput for all processes $\frac{8+24+3+10+11}{5}=11.2 ms$
Efficiency $\frac{25}{\left ( 2\times 5 \right )+\left ( 4\times 4 \right )+8}\times 100=73.5 ms$
https://www.youtube.com/watch?v=cApdURNWJPc
https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/5_CPU_Scheduling.html