Round robin Scheduling

Four processes A, B, C and D are in a ready queue of a real time operating system. Round robin Scheduling is to be used.
Process A requires 430μS to complete and is executed every 850μS.
Process B requires 200μS to complete and is executed every 700μS.
Process C requires 250μS to complete and is executed every 600μS.
Process D requires 410μS to complete and is executed every 710μS.

The clock tick period is 145μs while the context switch period is 11μs.

Solution
In Round robin Scheduling, each process gets equal time and execution of the processes is in the order they were submitted. The time slice diagram for the above question is as shown:

Total time required for Process A:
145 + 11 + 145 + 11 + 145 + 11 +145 + 11 + 145 + 11 + 55 + 11 + 105 + 11 + 145 + 11 + 140 = 1258μS
Total time required for Process B:
145 + 11 + 145 + 11 + 145 + 11 +145 + 11 + 145 + 11 + 55 = 835μS
Total time required for Process C:
145 + 11 + 145 + 11 + 145 + 11 +145 + 11 + 145 + 11 + 55 + 11 + 105 = 951μS
Total time required for Process D:
145 + 11 + 145 + 11 + 145 + 11 +145 + 11 + 145 + 11 + 55 + 11 + 105 + 11 + 145 + 11 + 140 + 11 + 120 = 1389μS

Therefore, none of the processes met their timing requirements