Non-Pre-emptive Priority Scheduling

Duration: 12 min

This video lesson is available to enrolled students.

Return to /learn/SSC-JE-IMD-SCIENTIFIC-ASSISTANT-COMPUTER-SCIENCE/operating-system/cpu-scheduling/priority-scheduling/asset-non-pre-emptive-priority-scheduling after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. General Intelligence & Reasoning: Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Syllogisms, Venn Diagram, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Data Sufficiency, Puzzle Solving (Puzzles), Data Arrangement, Cubes & Dices, Calendar, Clock, Arithmetic, Number System, HCF LCM, Verbal Analogy (Word Based Analogy), Visual Recognition and Figure Completion, Paper Folding and Cutting, Transformation of Shapes, Clocks and Calendars, Direction Sense, Cubes and Dice, Patterns in Two-Dimensional Figures, Seating Arrangements, Analogy and Classification, Logical Deduction and Induction, Alphabet and Word Tests, Mathematical Operations, Series Completion, Simplification and Approximation, Coding and Decoding, Numerical Reasoning, Assembling and Grouping of Shapes, Three-Dimensional Patterns and Visualization, Vocabulary, Number System, Averages, Mixtures and Alligation, Simple and Compound Interest, Percentages, Algebra, Speed, Time and Distance, Seating and Arrangement Puzzles, Traverse Surveying, Order, Ranking and Sequence, Constraint Puzzles, Syllogisms and Venn Diagrams, Reading Comprehension, Critical Reasoning, Permutations and Combinations, Narrative Sequencing, Project Monitoring, Resources and Safety, Profit, Loss and Discount, Ratio and Proportion, Time and Work, Mensuration, Data Interpretation, Powers, Surds and Logarithms, Sequences and Series, Articles and Determiners, Sentence Completion, Data Sufficiency, Blood Relations, Simple Interest and Compound Interest, Mixture and Alligation, Sequence and Series (Series), Speed Time and Distance, Algebra, Profit and Loss, Powers and Exponents (Surds and Indices), Permutation and Combination
  2. General Awareness: Physics, Chemistry, Biology, History, Geography, Polity, Indian Economy, Environment, Static General Knowledge, GK- Current Affairs, Artificial Intelligence, MS Office Applications, Terms & Abbreviations, Keyboard Shortcuts, Evolution of Indian Banking (Banking & Financial Awareness), Emerging Tech Trends
  3. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus, Probability, Statistics, Signal Space and Optimum Detection, Probability, Statistics
  4. Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep, Number Systems and Codes, Registers and Counters, Boolean Algebra and Logic Gates, Microprocessors and Microcontrollers, Logic Families and CMOS Logic, Microprocessors, Logic Gates and Boolean Algebra, Minimization of Boolean Functions, Timing, Hazards and Testing, Logic Families, Combinational Logic Design, Arithmetic Circuits, Waveform Generators and Timer Circuits, Semiconductor Memories and Programmable Logic Devices, Combinational Logic Circuits, Latches and Flip-Flops, Finite State Machines, Sequential Circuits and State Machines, Minimization of Boolean Functions, Arithmetic Circuits, Latches and Flip-Flops, Number Systems and Codes, Registers and Counters
  5. Computer Organisation & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer, Register Transfer and Microoperations, Semiconductor Memories and Programmable Logic, Processor Organization and Instructions, Memory Hierarchy and Input/Output, Registers and Counters
  6. Programming & Data Structures: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, HTML Basics, OOPS with C++, Java, Object Oriented Technology
  7. Databases: 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, Database Security & Authorization
  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  9. Theory of Computation: 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
  10. Compiler Design: 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
  11. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Security, Windows OS, Distributed Systems, Unix OS, Linux OS
  12. Computer Networks: Introduction to CN, 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, Data Communication, Website, Browser & Services, Web Design & Development, Network Security, Cyber Threats and Malware Attacks, Cyber Safety and Security
  13. Full Length Mock Tests:
  14. Sectional Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a comprehensive lecture on Priority Scheduling in Operating Systems. The instructor begins by defining the algorithm, explaining that each process is assigned a priority number, and the CPU is allocated to the process with the highest priority. He clarifies that 'highest priority' can be represented by either the highest or lowest number depending on the system's convention. The lecture covers tie-breaking mechanisms using First-Come-First-Served (FCFS) order and notes that the algorithm supports both pre-emptive and non-pre-emptive versions. The second half of the video features a detailed numerical example involving six processes (P0 to P5). The instructor constructs a Gantt chart to determine the execution sequence based on priority values and arrival times. He then calculates the Completion Time (CT), Turn Around Time (TAT), and Waiting Time (WT) for each process using standard formulas, filling out a data table to demonstrate the final results.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the concept of Priority Scheduling. The slide text states: 'Here a priority is associated with each process. At any instance of time out of all available process, CPU is allocated to the process which possess highest priority (may be higher or lower number).' He explains that a priority number is assigned to every process. He writes 'P1 - 5' and 'P2 - 3' on the screen to illustrate that priority is just a number. He mentions that if priorities are equal, the tie is broken using FCFS order. He also states that there is no importance to seniority or burst time in this algorithm.

  2. 2:00 – 5:00 02:00-05:00

    The instructor elaborates on the characteristics of Priority Scheduling. He draws a diagram of a queue to visualize how processes wait. He emphasizes that the algorithm supports both non-pre-emptive and pre-emptive versions. He explains that the CPU is always given to the process with the highest priority among the available ones. He clarifies that 'highest priority' might mean the highest number (e.g., 8 is higher than 5) or the lowest number (e.g., 1 is higher than 5), depending on the specific implementation. He reiterates that burst time does not influence the scheduling decision, only the priority value matters.

  3. 5:00 – 10:00 05:00-10:00

    The lecture transitions to a numerical example. A table appears with columns: P. No, AT (Arrival Time), BT (Burst Time), Priority, CT, TAT, and WT. The data includes processes P0 through P5 with varying priorities. P3 has a priority of 8(H), indicating High priority. The instructor draws a Gantt chart at the bottom of the screen. He determines the execution order: P0 starts at t=1. At t=5, P3 (Priority 8) is selected. At t=10, P2 (Priority 7) is selected. At t=13, P5 (Priority 6) is selected. For P1 and P4, which both have Priority 5, he applies FCFS, so P1 runs before P4. He writes the sequence P0, P3, P2, P5, P1, P4 on the timeline.

  4. 10:00 – 11:39 10:00-11:39

    The instructor completes the numerical solution by calculating the metrics for each process. He fills the CT column: P0=5, P3=10, P2=13, P5=15, P1=17, P4=18. He then calculates TAT using the formula 'TAT = CT - AT'. For P0, TAT is 5-1=4. For P1, TAT is 17-2=15. He proceeds to calculate WT using 'WT = TAT - BT'. For P0, WT is 4-4=0. For P1, WT is 15-2=13. He fills the entire table row by row, pointing to the values and explaining the arithmetic for each process to ensure students understand how the final metrics are derived from the Gantt chart.

The video effectively bridges theory and practice in Priority Scheduling. It starts by establishing the core rule: CPU allocation is driven by priority numbers, not burst time or arrival time, though arrival time dictates availability. The instructor clarifies the ambiguity of 'highest priority' (high number vs low number) and the role of FCFS in tie-breaking. The practical application involves a step-by-step execution of a Gantt chart where the scheduler dynamically picks the highest priority process available at each time unit. The final segment focuses on performance evaluation, calculating Turn Around Time and Waiting Time for each process, reinforcing the formulas TAT = CT - AT and WT = TAT - BT. This progression ensures students understand both the logic of the scheduler and the method for evaluating its efficiency.

Loading lesson…