FCFS with Overhead

In the above Examples, we are assuming that all the processes are the CPU bound processes only. We were also neglecting the context switching time.

However if the time taken by the scheduler in context switching is considered then the average waiting time of the system will be increased which also affects the efficiency of the system.

Context Switching is always an overhead. The Following Example describeshow the efficiency will be affected if the context switching time is considered in the system.

Example

In the following Example, we are considering five processes P1, P2, P3, P4, P5 and P6. Their arrival time and Burst time are given below.

If the context switching time of the system is 1 unit then the Gantt chart of the system will be prepared as follows.

Given δ=1 unit;

The system will take extra 1 unit of time (overhead) after the execution of every process to schedule the next process.