Pre-emptive Vs Non-Pre-emptive Scheduling

Duration: 5 min

This video lesson is available to enrolled students.

Return to /learn/ISRO/operating-system/cpu-scheduling/basics-criteria/asset-pre-emptive-vs-non-pre-emptive-scheduling after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. General Aptitude & Reasoning: Number System, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Speed Time and Distance, Mixture and Alligation, Data Interpretation, Algebra, Probability, Permutation and Combination, Venn Diagram, HCF LCM, Divisibility Rules, Age Problems, Pipe and Cistern, Partnership, Linear Algebra, Sequence and Series (Series), Statistics, Powers and Exponents (Surds and Indices), Arithmetic, Mensuration and Geometry, Calculus, Trigonometry, Vectors, Speed Mathematics and Basic Mathematics, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analogy, Series (Number and Letter Series) (Numerical Relations and Reasoning), Puzzle Solving (Puzzles), Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Calendar, Seating Arrangements, Coding Decoding, Blood Relations, Directions (Direction Test), Clock, Analytical Reasoning (Counting Figures Reasoning), Ranking, Order and Sequence, Logical Sequence Of Words, Inequality, Data Sufficiency, Cubes & Dices
  3. Computer Networks & Cybersecurity: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware Basics, Network Security
  4. Programming, Data Structures & Algorithms: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, OOPS with C++, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  5. AI, Machine Learning, Big Data & Cloud: Emerging Tech Trends, Artificial Intelligence, Big Data Systems, Approaches to AI, Search Algorithms, Knowledge Representation, Cloud Computing
  6. Digital Logic & Computer Organization: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer
  7. TOC & Compiler: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory, Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  8. Discrete Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic
  9. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS, Linux OS, Distributed Systems
  10. Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, Object Oriented Technology, HTML Basics, JavaScript-Basics, Java, XML
  11. Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, Data Warehousing & Mining, Enhanced Data Models, NoSQL
  12. Other Recurring CS Topics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, Multimedia
  13. Live Classes: ISRO Live classes
  14. Full Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture focuses on the fundamental types of process scheduling in operating systems, specifically contrasting Non-Preemptive and Preemptive scheduling strategies. The instructor begins by defining Non-Preemptive scheduling, emphasizing that once a process is allocated the CPU, it retains control until it voluntarily releases it. This is illustrated through a state transition diagram where a process moves from Running to Terminated upon completion or to Blocked when waiting for I/O. The lecture then transitions to Preemptive scheduling, where the operating system can forcibly remove a process from the CPU. This section details four specific scenarios for CPU release, including completion, voluntary I/O requests, high-priority process arrival, and time quantum expiration. The instructor uses a modified state diagram to visually represent these transitions, highlighting the additional paths from Running back to Ready that characterize preemptive behavior.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces Non-Preemptive scheduling, defining it as a strategy where a process keeps the CPU until it releases it willingly. On-screen text explicitly states: 'Under Non-Pre-emptive scheduling, once the CPU has been allocated to a process, the process keeps the CPU until it releases the CPU willingly.' He explains that a process leaves the CPU only in two specific cases: first, when it completes execution (Termination state), and second, when it voluntarily performs I/O operations (Blocked state). He draws a state transition diagram showing the flow from Start to Ready, then to Running. From Running, he draws an arrow labeled '1' pointing to Terminated and another arrow labeled '2' pointing to Blocked, which then loops back to Ready. This visual aid reinforces the concept that the process is not forced out during execution, ensuring it runs to completion or until it explicitly requests a resource.

  2. 2:00 – 4:48 02:00-04:48

    The lecture shifts to Preemptive scheduling, where a process can be forced out of the CPU. The on-screen text reads: 'Under Pre-emptive scheduling, once the CPU has been allocated to a process, A process will leave the CPU willingly or it can be forced out.' The instructor lists four conditions for leaving the CPU: completion of execution, voluntary I/O operations, arrival of a high-priority process, and time quantum expiration. He updates the state diagram to show arrows labeled '3' and '4' moving from Running back to Ready, representing the forced preemption scenarios. He explains that unlike the previous model, the OS can interrupt the running process if a higher priority task arrives or if the time slice expires, forcing the process back into the Ready queue. This highlights the dynamic nature of preemptive systems where the scheduler has more control over resource allocation.

The video effectively contrasts two core scheduling philosophies. Non-preemptive scheduling relies on the process's voluntary cooperation to release the CPU, limiting transitions to completion or I/O waits. Preemptive scheduling introduces OS control, allowing the system to interrupt running processes for higher priority tasks or time limits. The visual progression from a simple state diagram to a more complex one with additional feedback loops clearly demonstrates the increased flexibility and complexity of preemptive systems. Understanding these distinctions is crucial for analyzing system performance and responsiveness in operating system design.

Loading lesson…