Earliest Deadline First Scheduling Algorithm - example #1

Summary

In this video, Najib from Algeria explains the Earliest Deadline First (EDF) scheduling algorithm using three processes: T1, T2, and T3. He illustrates how to schedule these processes within a 20-time unit frame, emphasizing the importance of deadlines for efficient execution. By demonstrating the scheduling steps and how to prioritize tasks based on their deadlines, Najib clarifies the EDF method's functionality and resets for new periods. The video encourages viewers to subscribe for further examples and insights into scheduling algorithms.

Takeaways

• 😀 The Earliest Deadline First (EDF) scheduling algorithm prioritizes processes based on their deadlines.
• 😀 The example features three processes: T1, T2, and T3, each with specific capacities, deadlines, and periods.
• 😀 The LCM of the periods (20, 10, 5) is calculated to define the scheduling window, which is 20 time units.
• 😀 Process T1 has a period of 20 units and a deadline of 7 units.
• 😀 Process T2 has a period of 10 units and a deadline of 8 units.
• 😀 Process T3 has a period of 5 units and a deadline of 5 units.
• 😀 The scheduling begins with the process that has the nearest deadline, executing one time unit at a time.
• 😀 If a process's capacity is completed, it is marked as done and its remaining time is updated.
• 😀 The processor can remain idle if no processes are ready to execute, waiting for the next period to start.
• 😀 The video also mentions that additional examples and a C program related to the EDF algorithm can be found in the description.

Q & A

What is the main focus of Najib's video?

The video focuses on explaining the earliest deadline first (EDF) scheduling algorithm.

How many processes are discussed in the video?

Three processes are discussed: T1, T2, and T3.

What is the significance of the LCM mentioned in the video?

The LCM of the periods (20, 10, and 5) is 20, indicating that the scheduling cycle will repeat every 20 time units.

What are the active time periods for each process?

T1 is active from 0 to 20, T2 from 0 to 10 and again from 10 to 20, and T3 from 0 to 5, 5 to 10, 10 to 15, and 15 to 20.

How are the deadlines for each process defined?

T1 has a deadline from 0 to 7, T2 from 0 to 8 (first period) and 10 to 18 (second period), and T3 from 0 to 4, 4 to 9, 10 to 14, and 15 to 19.

What steps are involved in the scheduling process?

The steps include initializing the schedule, checking for the closest deadline, executing the process for 1 unit of time, and updating the remaining capacity.

What happens when the processor has no processes to execute?

If no processes are available, the processor remains idle until new periods start.

How does the video illustrate the execution of processes?

The video illustrates the execution by detailing how each process is run in order of their deadlines, updating their capacities after each execution.

What does Najib suggest viewers do at the end of the video?

Najib invites viewers to subscribe for further examples and additional content related to the scheduling algorithm.

What is the overall goal of the EDF scheduling algorithm?

The overall goal of the EDF scheduling algorithm is to ensure that the processes are executed in a timely manner according to their deadlines.