FCFS Scheduling with Context Switching Overhead: Impact on Performance
Analyze the impact of context switching overhead on First-Come, First-Served (FCFS) scheduling. This tutorial demonstrates how context switching time affects completion time, turnaround time, and waiting time, providing a deeper understanding of scheduling algorithm performance and efficiency.
FCFS Scheduling with Context Switching Overhead
Considering Context Switching Time in FCFS
In previous examples of First-Come, First-Served (FCFS) scheduling, we ignored the time taken by the OS to switch between processes (context switching). However, context switching consumes CPU time. This overhead increases the average waiting time and reduces overall system efficiency. This section illustrates the impact of context switching on FCFS scheduling.
Example FCFS Calculation with Context Switching Overhead
Consider six processes (P1-P6) with the following arrival and burst times:
| Process ID | Arrival Time | Burst Time |
|---|---|---|
| P1 | 0 | 3 |
| P2 | 1 | 2 |
| P3 | 2 | 1 |
| P4 | 3 | 3 |
| P5 | 4 | 4 |
| P6 | 5 | 2 |
Assume a context switching time (δ) of 1 unit. The Gantt chart will show the execution sequence, including the overhead of context switching between processes. Calculations for completion time, turnaround time, and waiting time would then be performed. The total execution time will increase by 1 unit (context switching overhead) for each process, resulting in a longer total processing time and affecting the efficiency of the system.
The efficiency and inefficiency of the system can then be calculated using the total processing time including overhead.