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
Now Reading
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
Assume the role of a chef for a moment. There you are – working in an extremely busy kitchen. You have orders pouring in from all around you – and each of different levels of importance.
Some orders from crucial customers are extremely important and call for prioritization.
How would you make certain that these high-priority orders are served first without neglecting or overlooking any?
Well, however you do it, in the world of operating systems, this is done using what is known as priority scheduling in OS. In this tutorial, I will walk you through all the nuances of priority scheduling in OS, along with priority scheduling algorithm in OS, priority scheduling example, and more! So, let’s begin.
Priority scheduling in OS, a method that operating systems use for deciding the order in which processes get run, is somewhat similar to giving some processes a more important status or priority than others. It's like having a "VIP lane" in the queue where high-priority processes can jump ahead and be treated with preference.
In priority scheduling, every process gets a priority value. This can be either fixed priority or dynamic priority that changes with time. The operating system then chooses the process having highest importance to execute next for getting access to CPU and other resources of the system.
The priority scheduling algorithm in OS manages the order of execution for processes according to their priorities. It is a basic rule: the process with the highest priority will be run first. When more than one process possesses identical priority, they are usually scheduled using a first-come, first-serve (FCFS) method within this level of priority.
Here's a step-by-step breakdown of the priority scheduling algorithm in OS:
The operating system makes certain that high-priority processes get special treatment and are executed ahead of lower-priority processes by using these types of priority scheduling algorithm in OS.
Preemptive priority scheduling algorithm works like a variant of the priority scheduling algorithm, where a process that is currently running can be interrupted and substituted by another process with higher priority. It's similar to when a VIP guest comes in at a restaurant—they are given a seat right away, even if it means asking someone else to wait for their place.
In preemptive priority scheduling, the operating system always checks the ready queue for any new processes with higher priority. If a process of higher priority arrives while another process with lower priority is running, the operating system interrupts this current process. It saves its state and begins executing the new process that has arrived with higher importance.
Here's a preemptive priority scheduling example:
Imagine we have three processes: P1 (priority 3), P2 (priority 1) and P3 (priority 2). In the beginning, process P1 begins executing. Now, after a little time has passed, process P2 comes in with more importance. The operating system takes away control from P1, saves its condition, and then begins executing P2. After some time, P3 comes with a higher priority than P1 but is lower compared to that of P2. It is put in the ready queue, and when P2 finishes the execution cycle, then we start processing it. Finally, P1 resumes its execution after P3 completes.
Firstly, preemptive priority scheduling ensures that high-priority processes are given instant attention. This occurs regardless of whether they are running or not and can interrupt the execution of processes with lower priority.
If you wish to learn more about the details of priority scheduling and other process scheduling algorithms, I suggest you explore upGrad’s offerings in the domain of computer science. These courses include everything from OS, programming, database management, and more!
Now, I’ll explain priority scheduling algorithm with example. For incorporating priority scheduling into an operating system, we can create a program to handle the ready queue. This program will pick out the process possessing the greatest priority for execution. Here is a basic priority scheduling algorithm example in OS:
function PriorityScheduling(processes):
while not isEmpty(processes):
highestPriorityProcess = findHighestPriorityProcess(processes)
execute(highestPriorityProcess)
remove(highestPriorityProcess, processes)
end while
end function
function findHighestPriorityProcess(processes):
highestPriorityProcess = processes[0]
for each process in processes:
if process.priority > highestPriorityProcess.priority:
highestPriorityProcess = process
end if
end for
return highestPriorityProcess
end function
In the pseudocode, the PriorityScheduling function keeps on finding a process with maximum priority using findHighestPriorityProcess function, executing and taking it out from the list of processes until all are finished.
The function findHighestPriorityProcess runs a loop through the list of processes and gives back the process having the highest priority.
Certainly, this is a basic form, and real versions could have more characteristics such as preemption, dynamic priority changes and dealing with many processes having equal priorities.
For a deep look into the inner workings of priority scheduling in OS and other scheduling algorithms, you may find upGrad's courses worth considering. The courses are designed to give you practical knowledge on how to implement different scheduling algorithms and comprehend their actions in actual situations.
Priority based scheduling algorithm offers several benefits and meets certain requirements in operating systems:
But, there are also a few setbacks to this method. It might cause starvation of lower-priority processes when higher-priority processes keep coming in, not allowing the lower ones to get any CPU time. Moreover, giving correct priorities to processes can be difficult and needs deep thought so as to prevent priority inversion and guarantee fair scheduling.
Priority scheduling in OS is a major concept that underlies process execution order according to given priorities. This technique, by giving more importance to high-priority processes, makes sure vital tasks are handled first: it improves system response time and meets needs for execution based on importance.
Learning about priority scheduling is necessary for someone who enjoys working with operating systems to comprehend how processes are handled in real-world systems. It serves as a base for designing and enhancing operating systems that can manage different types of workloads appropriately and fulfill the requirements of present-day computing.
The courses from upGrad, covering memory management, file systems, and synchronization, along with other interesting subjects like computer science, software engineering, and more, are recommended to those who wish to explore the world of operating systems. These complete learning pathways will assist you in becoming a genuine expert in this field.
Keep on discovering, keep learning, and above all else, continue putting your love for operating systems at the forefront. Perhaps someday, you will design a new significant scheduling algorithm that transforms how computing is done.
Good luck with your scheduling, and may your processes always end up at the top of the priority queue!
The priority level in OS represents the process's importance or urgency. It decides the sequence of processes that run, prioritizing high-priority processes over low-priority ones.
Preemptive priority scheduling gives permission for an ongoing process to get interrupted and substituted with a more important one, making sure crucial tasks are handled right away. Non-preemptive priority scheduling, in contrast, permits a process to finish its execution before switching to the next highest-priority one. This remains true even when a higher-priority process arrives during this period of time.
The three different types of scheduling queues are:
Priority-driven scheduling is another term for priority scheduling. It is a scheduling method that organizes processes by their given priorities, with those with more priority getting better treatment than lower-priority processes.
Non-preemptive priority scheduling is a type of prioritized scheduling in which the currently running process can complete its task before the scheduler chooses the next process with the highest priority. If a process of lower priority is running and one with higher priority comes in, the scheduler will wait for the current process to finish before it swaps to the incoming high-priority one.
The three most used priority levels are:
Priority scheduling ensures that processes with greater significance or emergencies are executed before processes with lower priority. It allows the operating system to focus on important tasks, enhance system quickness in response, and fulfill importance-related execution needs.
The major problem with priority scheduling is that it can cause starvation. When processes with higher priority keep coming in, those processes with lower priority might be delayed indefinitely. This can cause starvation, which means that these less important processes do not get enough time on the CPU or resources to finish their execution.
This is a hybrid scheduling algorithm that uses both priority scheduling and the round-robin method. In this method, processes are arranged according to their importance level. If two or more processes have equal priority, we use the round-robin algorithm to arrange them. This means that every process receives a fixed amount of time quantum for execution before moving on to the next process with identical priority.
Advantages of priority scheduling include:
Disadvantages of priority scheduling include:
Amit Chandra
Amit Chandra, PMP, SCPM, is a program and product management professional with over 15 years of experience in publishing, EDA and Insurance domai…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...