Table of Contents
CPU scheduling algorithms determine how processes are assigned to the CPU, affecting system performance and responsiveness. Understanding their practical calculations helps in selecting the appropriate algorithm for specific scenarios.
Types of CPU Scheduling Algorithms
Common algorithms include First-Come, First-Served (FCFS), Shortest Job Next (SJN), Round Robin (RR), and Priority Scheduling. Each has different methods for selecting the next process to execute.
Performance Metrics
Key metrics for evaluating scheduling algorithms are waiting time, turnaround time, and CPU utilization. Calculations often involve process burst times and arrival times.
Practical Calculation Example
Consider three processes with burst times of 5, 3, and 8 units arriving at time 0. Using FCFS, the total waiting time is calculated by summing the idle times between processes.
For FCFS:
- Process 1: waits 0 units
- Process 2: waits 5 units
- Process 3: waits 8 units
Total waiting time = 0 + 5 + 8 = 13 units. Average waiting time = 13 / 3 ≈ 4.33 units.
Trade-offs in Scheduling
Different algorithms balance fairness, efficiency, and response time. For example, Round Robin improves responsiveness but may increase context switching overhead. Priority scheduling can lead to starvation if not managed properly.