Question

Draw a Gantt chart that shows the completion times for each process
using shortest job next CPU scheduling.
process p1|p2|p3|p4|p5|
service time |120|60|180|50|300

Answer 1

To create a Gantt chart for CPU scheduling using the Shortest Job Next (SJN) algorithm, we first need to sort the processes by their service times in ascending order. The service times for the processes are as follows:

- **p1**: 120
- **p2**: 60
- **p3**: 180
- **p4**: 50
- **p5**: 300

### Step 1: Sort Processes by Service Time
1. **p4**: 50
2. **p2**: 60
3. **p1**: 120
4. **p3**: 180
5. **p5**: 300

### Step 2: Create Completion Times
Next, we calculate the completion time for each process based on our sorted list.

- **Completion Time for p4**: 50
- **Completion Time for p2**: 50 + 60 = 110
- **Completion Time for p1**: 110 + 120 = 230
- **Completion Time for p3**: 230 + 180 = 410
- **Completion Time for p5**: 410 + 300 = 710

### Step 3: Gantt Chart Representation
Now, we can represent this data in a Gantt chart. The Gantt chart shows the scheduling of processes over time.

```
| p4 | p2 | p1 | p3 | p5 |
0 50 110 230 410 710
```

### Summary of Completion Times
- **p4**: 50
- **p2**: 110
- **p1**: 230
- **p3**: 410
- **p5**: 710

### Gantt Chart Visualization

```
| p4 | p2 | p1 | p3 | p5 |
0 50 110 230 410 710
```

This Gantt chart illustrates the order of process execution based on the Shortest Job Next CPU scheduling algorithm.