1. Latest Deadline First (LDF) Given the precedence graph in Figure 1 and the following table of task execution times and deadlines, determine the Latest Deadline First (LDF) schedule. C₁ Di J₁ J2 J3 J4 J5 J6 J7 J8 3 3 3 2 2 1 15 12 18 19 20 35 48 4 2 8 11

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### Latest Deadline First (LDF) Scheduling

**Objective:**
Given the precedence graph and the following table of task execution times and deadlines, determine the Latest Deadline First (LDF) schedule.

**Table of Task Execution Times and Deadlines:**

| Task (Ji) | J1 | J2 | J3 | J4 | J5 | J6 | J7 | J8 |
|-----------|----|----|----|----|----|----|----|----|
| Execution Time (Ci) | 3 | 4 | 2 | 3 | 3 | 2 | 1 | 1 |
| Deadline (Di)       | 5 | 8 | 11 | 15 | 12 | 18 | 19 | 20 |

**Figure 1: Task Precedence Graph**

The precedence graph indicates the order in which tasks must be performed, visualized as a directed graph where each node represents a task and directed edges indicate precedence constraints. 

**Explanation of the Graph:**

- The graph consists of 8 circular nodes labeled from \(J_1\) to \(J_8\).
- Arrows (directed edges) connect these nodes, indicating the dependencies between tasks.
- If there is a directed edge from node \(J_i\) to node \(J_j\), task \(J_j\) cannot start until task \(J_i\) is completed.

The goal is to create a schedule where tasks are arranged according to their deadlines, ensuring that all precedence constraints are satisfied and tasks are executed as late as possible without violating their respective deadlines.

Instructions for determining the LDF schedule:
1. **Identify Deadlines:** Extract deadlines from the given table.
2. **Sort by Deadlines:** Arrange the tasks in decreasing order of deadlines.
3. **Check Precedence Constraints:** Ensure that all preceding tasks (based on the graph) are scheduled before their dependent tasks.
4. **Formulate Schedule:** Allocate execution times in a sequence that respects the precedence constraints and minimizes the slack time before deadlines.

By following the principles of the LDF scheduling algorithm, we can effectively manage task sequencing in complex systems with interdependent activities.
Transcribed Image Text:### Latest Deadline First (LDF) Scheduling **Objective:** Given the precedence graph and the following table of task execution times and deadlines, determine the Latest Deadline First (LDF) schedule. **Table of Task Execution Times and Deadlines:** | Task (Ji) | J1 | J2 | J3 | J4 | J5 | J6 | J7 | J8 | |-----------|----|----|----|----|----|----|----|----| | Execution Time (Ci) | 3 | 4 | 2 | 3 | 3 | 2 | 1 | 1 | | Deadline (Di) | 5 | 8 | 11 | 15 | 12 | 18 | 19 | 20 | **Figure 1: Task Precedence Graph** The precedence graph indicates the order in which tasks must be performed, visualized as a directed graph where each node represents a task and directed edges indicate precedence constraints. **Explanation of the Graph:** - The graph consists of 8 circular nodes labeled from \(J_1\) to \(J_8\). - Arrows (directed edges) connect these nodes, indicating the dependencies between tasks. - If there is a directed edge from node \(J_i\) to node \(J_j\), task \(J_j\) cannot start until task \(J_i\) is completed. The goal is to create a schedule where tasks are arranged according to their deadlines, ensuring that all precedence constraints are satisfied and tasks are executed as late as possible without violating their respective deadlines. Instructions for determining the LDF schedule: 1. **Identify Deadlines:** Extract deadlines from the given table. 2. **Sort by Deadlines:** Arrange the tasks in decreasing order of deadlines. 3. **Check Precedence Constraints:** Ensure that all preceding tasks (based on the graph) are scheduled before their dependent tasks. 4. **Formulate Schedule:** Allocate execution times in a sequence that respects the precedence constraints and minimizes the slack time before deadlines. By following the principles of the LDF scheduling algorithm, we can effectively manage task sequencing in complex systems with interdependent activities.
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