Tutorial Playlist
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
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
Now Reading
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
Imagine yourself as a chef in a very busy kitchen, managing many different dishes that need attention at different times. Now, an important order from a VIP customer has arrived, and it needs to be worked on right away.
What would you do? You give the VIP order attention first and delay other dishes until it has finished.
This is what we mean by preemptive priority scheduling, and this is essentially what a preemptive priority scheduling algorithm does in operating systems!
I am excited to tell you more about preemptive priority scheduling in this tutorial. So, let’s begin!
In the culinary world of operating systems, we can compare the preemptive priority scheduling algorithm to a severe head chef who always guarantees that the most important dishes (processes) are served first, regardless of whether other tasks are being prepared. It's a method for arranging a time when every process gets one priority, and the processing unit (CPU) is given to the process having the highest priority, with the ability to stop the ongoing process if needed.
The preemptive priority scheduling algorithm, a method based on priority, brings in the idea of preemption. Preemption implies that when a process with higher priority comes, it can interrupt the lower-priority process currently running and take over control of the CPU. This method guarantees that essential processes are dealt with instantly and not delayed for an indefinite time period.
Now, to comprehend the preemptive priority scheduling algorithm, we can contrast it with non-preemptive priority scheduling.
In non-preemptive priority scheduling, when a process begins running it carries on until finished or willingly gives up the CPU. It does not matter if another process with higher importance arrives during this time period. This behavior is similar to a chef who does not wish to stop preparing one meal for another, even if the latter order is more urgent.
However, with preemptive priority scheduling, the operating system can step in and take away the currently running process if a process of higher priority comes. It's similar to how a head chef might quickly shift gears and prioritize the VIP order, putting other dishes on hold.
To understand how preemptive priority scheduling functions, let us examine an example. Suppose we have three processes: P1 (priority 3), P2 (priority 1), and P3 (priority 2). The following sequence shows the arrangement:
This example shows how the preemptive priority scheduling algorithm makes sure processes with higher priority are given more importance and can interrupt lower-priority process execution.
For a non preemptive priority scheduling case, we can use the same three processes: P1 (priority 3), P2 (priority 1), and P3 (priority 2). This is how the scheduling would go:
In this non preemptive scheduling situation, even if processes P2 and P3 have higher priorities, they must wait for process P1 to finish before starting execution.
When you apply or study the algorithm of preemptive priority scheduling, it's crucial to think about these questions:
Answering these preemptive priority scheduling questions helps in designing an effective and robust preemptive priority scheduling system.
If the above questions make you curious, you should check out upGrad’s courses on computer science and engineering. Covering all important domains, including operating systems, these courses are designed to take you up from the very basics to a level where you comfortably understand all the important concepts and are in a position to apply your knowledge to real-world problems. Check out the courses and enroll yourself soon!
The preemptive priority scheduling algorithm is a strong method used in operating systems to make sure that tasks with high priority are given instant attention and run without delay. This technique is beneficial because it permits preemption, which allows the system to promptly respond to critical jobs and efficiently use CPU time.
In this tutorial, we have studied the idea of preemptive priority scheduling, compared it with non-preemptive scheduling and talked about its benefits as well as drawbacks. We also saw some instances to show how the algorithm functions in real life.
For someone who wants to become an expert in operating systems, knowing scheduling algorithms such as preemptive priority scheduling is very important. It helps with the basics of creating effective and quick systems that can handle different workloads and match what is needed for today's computing.
If you're excited about operating systems and want to learn more in areas like memory management, file systems, and synchronization, I suggest looking at the different courses from upGrad. They cover many topics related to operating systems and beyond, from computer science to software engineering. You can choose a complete learning journey with upGrad that will guide you toward becoming an expert in all things related to operating systems.
Continue to explore, continue to learn, and, above all else, keep accepting the art of process scheduling. Perhaps in the future, you could be the one who creates the next innovative scheduling algorithm that changes everything in operating systems around the world!
Happy scheduling, and may all your operations consistently make it to the front of the priority queue!
Preemptive priority scheduling is a kind of scheduling algorithm that gives a priority to every process. The CPU is given to the process with the highest priority. If there comes a higher-priority process while one with lower priority is working, we stop the lower-priority task (preempt it), so that it can start executing straight away.
Programs in C that apply priority scheduling with preemption mean the usage of C programming language to create programs that demonstrate the functioning of a preemptive priority scheduling algorithm. This includes making a program that shows how the algorithm works, providing priorities for processes, and dealing with preemption when processes of higher priority arrive.
An instance of preemptive scheduling can be seen when there is a process with high priority, like a real-time system interrupt, that comes while another process of lower priority is running. The algorithm for preemptive scheduling will at once preclude the lower-priority operation and assign the CPU time towards this high-priority task. This guarantees rapid treatment for the interrupt.
Preemptive scheduling ensures that high-priority processes get immediate attention and are executed promptly. This helps the operating system to react quickly, use CPU effectively, and give better response time for users. Preemptive scheduling is very helpful in real-time systems and settings where some processes have strict timing limits.
Preemptive scheduling algorithms have different types, such as Round Robin with Preemption, Shortest Remaining Time First (SRTF), Preemptive Priority Scheduling, and Earliest Deadline First (EDF). These methods are distinct in how they decide which process to preempt and assign the CPU time to. This decision is made according to factors like time quantum, remaining execution time, priorities, or deadlines.
Some drawbacks of preemptive scheduling are context-switching overhead, priority inversion, starvation, and more complexity. Preemption needs to save and restore process states, which adds some overhead. When a high-priority process gets blocked because it's waiting for a resource held by a low-priority one, this condition is called priority inversion. Processes with lower priority could experience starvation if there is a constant arrival of high-priority processes. The introduction of preemption in scheduling algorithms can be more complicated than non-preemptive algorithms because it requires synchronization and dealing with preemption issues.
The Shortest Job First (SJF) scheduling algorithm can be preemptive or non-preemptive. In a preemptive setting, which is also referred to as Shortest Remaining Time First (SRTF), an incoming process with less remaining execution time can interrupt the current one. In a non-preemptive setting, once a process starts running, it will keep going even if another shorter process comes in.
To solve the preemptive priority scheduling, you must do these steps: give priorities to each process according to their importance or urgency; sort all processes in the ready queue by their priority; give CPU to the process having the highest priority; if a new process comes with more high priority than running one then it should be replaced and when any lower-priority process completes, or a higher-priority arrives, continue executing the previously preempted one. Repeat this procedure until all processes are finished.
The benefits of preemptive scheduling methods are quicker response, better use of resources, flexibility and prevention of starvation. Processes with high priority get immediate attention so that important tasks can be handled promptly. The time of CPU is efficiently used by processes with high priority which reduces the idle periods. The system can adjust priorities in a flexible manner according to changing requirements, permitting it to adapt. Preemption enables lower-priority processes to execute when high-priority processes are not running, which stops infinite starvation.
No, the First-In-First-Out (FIFO) scheduling algorithm, which is also called First-Come-First-Served (FCFS), does not stop processes. In this algorithm, processes are executed in the sequence they arrive at, and when a process starts running it goes on until finished without getting interrupted by other processes. FIFO doesn't involve any concept of priority for processes or allow preemption based on priority.
Rohan Vats
Passionate about building large scale web apps with delightful experiences. In pursuit of transforming engineers into leaders.
Talk to our experts. We’re available 24/7.
Indian Nationals
1800 210 2020
Foreign Nationals
+918045604032
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 enrolling. upGrad does not make any representations regarding the recognition or equivalence of the credits or credentials awarded, unless otherwise expressly stated. Success depends on individual qualifications, experience, and efforts in seeking employment.
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...