ALGORITMA CPU SCHEDULING | SISTEM OPERASI

Summary

In this video, Giovan Lado, Bayu Brigas Novaldi, and Andika Rahman Pratama explore the core concepts of CPU scheduling algorithms, explaining how they affect system performance. They compare four major algorithms: First-Come, First-Serve (FCFS), Shortest Job First (SJF), Round Robin (RR), and Priority Scheduling. Each algorithm is explained with practical examples and performance metrics, such as response time, waiting time, and turnaround time. The video demonstrates how efficient scheduling enhances system responsiveness, offering insights into the strengths and weaknesses of each algorithm in different computational scenarios.

Takeaways

• 😀 CPU scheduling is a crucial concept in operating systems that helps manage the execution of multiple processes efficiently.
• 😀 Primitive scheduling allows processes to be interrupted and moved between different states, while non-primitive scheduling does not allow interruptions once a process starts running.
• 😀 First Come First Serve (FCFS) schedules processes in the order they arrive, but may lead to high waiting times, especially for longer processes.
• 😀 Shortest Job First (SJF) prioritizes processes with the shortest execution time, improving response times but requiring knowledge of process lengths ahead of time.
• 😀 Round Robin (RR) allocates a fixed time slice (quantum) to each process, ensuring fairness but potentially reducing efficiency for processes with varied time needs.
• 😀 Priority Scheduling executes processes based on priority, where processes with lower priority values are executed first, but can lead to starvation if lower-priority processes are always preempted.
• 😀 FCFS results in an average response time of 10 seconds, an average waiting time of 10.8 seconds, and an average turnaround time of 17.2 seconds.
• 😀 SJF results in an average response time of 4.6 seconds, an average waiting time of 7.4 seconds, and an average turnaround time of 13.8 seconds.
• 😀 Round Robin scheduling with a 3ms quantum time produces response times ranging from 0ms to 9ms, ensuring fairness in process execution.
• 😀 Priority Scheduling uses process priority values, where processes with lower priority numbers are executed first, and results in a wide variation in response times, from 0ms to 19ms.

Q & A

What is CPU scheduling, and why is it important in operating systems?

CPU scheduling is the process of deciding which task or process the CPU should execute next. It's important because it allows the operating system to efficiently manage multiple processes, ensuring that the system runs smoothly, responsively, and efficiently, providing a better user experience.

What is the difference between primitive and non-primitive scheduling?

In non-primitive (cooperative) scheduling, a process runs to completion or enters a waiting state without being interrupted by the operating system. In primitive (preemptive) scheduling, a running process can be interrupted and replaced by another process, giving the operating system full control over process execution.

How does cooperative scheduling work?

Cooperative scheduling works by allowing processes to execute to completion or enter a waiting state without being interrupted. The operating system does not control the execution of processes in this mode.

What is the purpose of CPU scheduling algorithms?

The purpose of CPU scheduling algorithms is to manage the order in which processes are executed on the CPU. These algorithms aim to maximize CPU utilization, reduce waiting time, and improve overall system performance and user experience.

How does the First-Come-First-Serve (FCFS) algorithm work?

The FCFS algorithm schedules processes in the order they arrive. The first process to arrive is executed first, followed by the next, and so on. It is a simple algorithm but can lead to inefficiencies like long waiting times for processes that arrive later.

What are the results of applying the First-Come-First-Serve (FCFS) scheduling algorithm in the provided example?

The response times for the processes were: P1 = 0 ms, P2 = 8 ms, P3 = 11 ms, P4 = 17 ms, and P5 = 18 ms. The average response time was 10 ms, the waiting time was 10.8 ms, and the turnaround time was 17.2 ms.

What is Shortest Job First (SJF) scheduling, and how does it work?

Shortest Job First (SJF) scheduling prioritizes processes with the shortest burst times. Processes are executed based on the shortest execution time required, leading to minimized average waiting times and higher efficiency, though it requires knowledge of burst times.

What are the results of applying the Shortest Job First (SJF) algorithm in the example?

The response times for the processes were: P1 = 0 ms, P2 = 1 ms, P3 = 5 ms, P4 = 6 ms, and P5 = 9 ms. The average response time was 4.6 ms, the waiting time was 7.4 ms, and the turnaround time was 13.8 ms.

How does the Round Robin (RR) scheduling algorithm work?

Round Robin (RR) scheduling assigns a fixed time slice or quantum to each process. When a process’s time slice expires, it is preempted, and the next process is executed. This cycle continues until all processes are completed.

What are the results of applying the Round Robin (RR) algorithm in the example?

The response times for the processes were: P1 = 0 ms, P2 = 1 ms, P3 = 5 ms, P4 = 6 ms, and P5 = 9 ms. The algorithm cycles through processes with fixed time slices, ensuring fair distribution of CPU time.

What is Priority Scheduling, and how does it differ from the other algorithms?

Priority Scheduling assigns each process a priority value. Processes with higher priority (lower numerical value) are executed first. This differs from algorithms like FCFS and SJF, which do not take priority into account.

What are the results of applying the Priority Scheduling algorithm in the example?

The response times for the processes were: P1 = 0 ms, P2 = 0 ms, P3 = 15 ms, P4 = 1 ms, and P5 = 19 ms. This scheduling method ensures that higher-priority processes are executed before lower-priority ones, impacting the response time based on priority levels.

How do the performance metrics (response time, waiting time, and turnaround time) differ across the algorithms?

In general, algorithms like SJF tend to have lower average response and waiting times because they prioritize shorter burst times. Round Robin, while fair, may result in higher turnaround times due to frequent preemptions. FCFS tends to have higher waiting times for processes that arrive later, and Priority Scheduling depends heavily on the assigned priority values.