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47 Lessons1. Introduction to Operating System
2. Types of Operating Systems
3. Linux Operating System
4. An Introduction To Unix Operating System
5. Ubuntu Operating System
6. MS DOS Operating System
7. Mobile Operating System
8. Understanding Functions of Operating System
9. Components of Operating System
10. Understanding the Kernel in Operating Systems
11. Structure of Operating System
12. Process in Operating System
13. What is Bios
14. What is Booting in Computer
15. What is Interrupt in Operating System?
16. Process Control Block in Operating Systems
17. Threads in Operating System
18. Process Synchronization in OS
19. Critical Section in OS
20. Semaphore in Operating System
21. Deadlock in Operating System
22. Deadlock Prevention in OS
23. Paging in Operating System
24. Segmentation in Operating System
25. Virtual Memory in Operating System
26. File System in Operating Systems
27. Page Table in OS
28. Round Robin Scheduling in Operating System
29. Shortest Job First Scheduling Algorithm
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30. Priority Scheduling in OS
31. Page Replacement Algorithms in Operating System
32. Race Condition in OS
33. Distributed Operating System
34. Navigating Contiguous Memory Allocation in Operating Systems
35. Fragmentation in Operating System
36. Banker’s Algorithm in OS
37. Context Switching in OS
38. First Come First Serve (FCFS) Scheduling Algorithm in Operating System
39. Understanding Inter Process Communication in OS
40. Multiprogramming Operating System
41. Python OS Module
42. Preemptive Priority Scheduling Algorithm
43. Resource Allocation Graph in OS
44. Scheduling Algorithms in OS
45. System Calls In Operating System
46. Thrashing in Operating Systems: A Deep Dive
47. Time Sharing Operating System
Hello OS lovers! It is time to jump into the universe of process scheduling algorithms.
Here, I will walk you through the nuances of the shortest job first scheduling algorithm. It is one of the most interesting and productive algorithms when it comes to process scheduling in OS. The SJF scheduling algorithm in OS also forms the foundation for other more advanced scheduling methods.
So, let’s begin our journey into the world of shortest job first scheduling algorithm, and understand SJF scheduling algorithm, SJF preemptive scheduling example, and also look at the shortest job first scheduling program in OS.
Let’s start!
You are a chef in a busy kitchen, handling many orders at the same time. How do you determine which order to prepare first? Well, if you prefer efficiency, it could be that you decide to deal with the easiest orders initially so customers can get their food quickly. This is the primary concept of the shortest job first scheduling algorithm in operating systems, also known as the SJF scheduling algorithm in OS.
The SJF scheduling algorithm is a non-preemptive algorithm. It picks the process having the shortest burst time to execute next. For an analogy, imagine a clever chef who always picks the fastest dishes to cook. This reduces the average waiting time for all orders.
The SJF scheduling algorithm in OS, therefore, works by minimizing the average waiting time and turnaround time of processes. This works by highlighting shorter processes first which keeps the system responsive and effective, reducing overall time spent on queue wait for processes.
The SJF scheduling algorithm has several advantages that make it an attractive choice for process scheduling in operating systems. Let's explore a few of them:
If you have an interest in learning more about the benefits of SJF and how it stands against other scheduling algorithms, I suggest looking at upGrad's courses in the world of computer science. The courses offer a detailed introduction to different scheduling methods and what they give up for gaining advantages.
Though the SJF scheduling algorithm in OS has its plus points, it also has some downsides. Let's see its disadvantages:
To grasp the functioning of the SJF scheduling algorithm, let's contemplate on a straightforward illustration. Imagine we possess these processes along with their burst times:
Using the SJF algorithm, the execution order would be as follows:
From the burst times, we can see that the order of processing starts with the shortest process (Process B), then proceeds to the next shortest (Process D), and so on. By doing this, the average waiting time is reduced and it guarantees quicker completion for shorter processes.
In the operating system, we can write a program to hold and manage a queue of processes. It will choose the process with the smallest burst time for execution. Here is an example of simplified pseudocode for the shortest job first scheduling program in OS:
function SJF_Scheduling(processes):
while not isEmpty(processes):
shortestProcess = findShortestProcess(processes)
execute(shortestProcess)
remove(shortestProcess, processes)
end while
end function
function findShortestProcess(processes):
shortestProcess = processes[0]
for each process in processes:
if process.burstTime < shortestProcess.burstTime:
shortestProcess = process
end if
end for
return shortestProcess
end function
For this shortest job first scheduling algorithm pseudocode, the SJF_Scheduling function repeats the process of finding the shortest burst time using the findShortestProcess function, executing it, and removing it from the list of processes until all processes are finished.
If you are curiosity about the workings of SJF and other scheduling methods, I suggest looking at upGrad's list of courses today! You’ll surely find a course that will fit your needs.
You have arrived at the conclusion of this thrilling adventure through the domain of Shortest Job First (SJF) scheduling algorithm! We have examined basic aspects about SJF, its strong points and limitations. Moreover, we observed an illustration on how it functions in reality.
I, who have great interest in the field of operating systems, am quite fascinated by the elegance and effectiveness of SJF. The main goal of SJF is to give priority to shorter processes which helps in reducing average waiting time and enhancing system's response. Nevertheless, we must not forget its drawbacks like the possibility for long processes to get starved and difficulties with predicting burst times accurately.
Understanding the ideas of process scheduling is very important for anyone who wants to be an expert in operating systems. It creates basic knowledge about how operating systems handle and improve the running of processes, making sure they work well and effectively.
For those who are enthusiastic about operating systems and want to study additional interesting subjects such as memory management, file systems, and synchronization, upGrad has a broad selection of courses. From Computer Science to Software Engineering and more, upGrad gives complete learning routes that can assist you in becoming an actual expert in operating systems.
Lastly, keep searching, keep gaining knowledge and above all else, continue to become absorbed in the amazing realm of operating systems. You may end up creating the next revolutionary scheduling method one day!
Happy coding, and may your processes always find the shortest path to execution!
The shortest job first (SJF) process scheduling algorithm is a non-preemptive method. It chooses the process with the smallest burst time (time of execution) to be executed next. This algorithm tries to reduce the average waiting time and enhance the system's responsiveness.
The SJF algorithm, which stands for Shortest Job First, can be put into action with the help of C. You need to keep a process queue and choose the shortest burst time among them for execution. This programming logic might be written utilizing arrays or different data structures that portray processes and their characteristics.
The initial scheduling algorithm is first come, first served (FCFS). This algorithm is usually seen as the easiest and earliest scheduling method. It runs processes based on their arrival sequence without taking burst times or priorities into account.
In SJF scheduling, processes are chosen based on their burst times, and the one with the shortest execution time is given priority. But in priority scheduling, priorities are assigned to processes, and the process with the highest priority is selected for execution even if its burst time is longer.
It can be both non-preemptive and preemptive. In the non-preemptive form, once a process starts executing it carries on until finished. In the preemptive version, which is also called shortest remaining time first (SRTF), a new coming process having a shorter burst time can interrupt the presently running process.
There's no one "best" scheduling algorithm. The selection depends on particular demands and features of the system, with each having its own advantages and disadvantages. The selection of an algorithm for a certain scenario is influenced by factors such as fairness, efficiency, response time and priority requirements.
Yes, the shortest job first (SJF) can be viewed as a greedy algorithm. This is because, at each step, the local best choice is made by picking the process with the minimum burst time. The main objective of SJF is to reduce average waiting time without taking into account how this selection may affect other processes in the long run.
In operating systems, SJF can be beneficial because it offers the least average wait time. This method also leads to a higher system reaction speed and better use of resources, along with lesser turnaround time by focusing on shorter processes.
Advantages of SJF include minimal average waiting time, shorter process time, better resource utilization, and reduced turnaround time.
The disadvantages of SJF include possible starvation for longer processes, uncertainty in predicting burst times, no priority consideration and the overhead connected with context switching in its preemptive version.
The decision to use either SJF or FCFS depends on the needs of the system. In general, SJF offers lower average waiting times and improved system responsiveness when compared to FCFS. However, FCFS has its own benefits. It's simple, easy to understand and implement. Processes are executed in the exact order they came in, so it guarantees fairness and stops any starvation issue. Determining which method is better depends on many things, such as the type of workload, the need for priority settings, and what trade-offs between fairness and efficiency are acceptable.
Abhimita Debnath
Abhimita Debnath is one of the students in UpGrad Big Data Engineering program with BITS Pilani. She's a Senior Software Engineer in Infosys. She…Read More
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upGrad does not grant credit; credits are granted, accepted or transferred at the sole discretion of the relevant educational institution offering the diploma or degree. We advise you to enquire further regarding the suitability of this program for your academic, professional requirements and job prospects before enr...