Non-Pre-emptive Priority Scheduling

Duration: 12 min

This video lesson is available to enrolled students.

Return to /learn/BPSC/operating-systems/cpu-scheduling/priority-scheduling/asset-non-pre-emptive-priority-scheduling after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Section 1 | Language (Hindi): भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
  3. Section 1 | Language (उर्दू भाषा — 22 प्रश्न (निश्चित)): Spelling & Diacritics, Grammar (اسم, فعل, صفت, ضمیر), Vocabulary, Idioms & Proverbs, Comprehension
  4. Section 1 | Language (বাংলা / बांग्ला भाषा — 22 प्रश्न (निश्चित)): Bangla Script and Sounds, Bangla Grammar and Usage, Bangla Word Formation and Vocabulary, Reading and Text Interpretation
  5. Section 1 | Language (English): Vocabulary, Noun, Subject Verb Agreement (Verb Noun Agreement), Adjectives, Tenses, Pronoun, Verb, Adverb, Preposition, Articles, Determiner, Conjunction, Modals, Active Passive Voice (Voice), Direct and Indirect Speech, Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Construction, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Verbal Analogy (Word Based Analogy), Facts, Inference and Judgements
  6. Section 2 | Primary Maths & Reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Mensuration and Geometry, Age Problems, Arithmetic, Powers and Exponents (Surds and Indices), Algebra, Probability, Trigonometry, Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence
  7. Section 2 | General Awareness (GK + Current Affairs): Polity, Physics, Biology, State Wise GK, Chemistry, History, Geography, Indian Economy, Environment, GK- Current Affairs, Static General Knowledge
  8. Section 3 | Computer System and Org. (CSO): Basics of COA, Floating Point Rep, Cache Memory Organization, Instr Formats & Modes, Programming the Basic Computer, Input Output Organisation, Register Transfer and Microoperations, Control Unit Design
  9. Section 3 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, SQL, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control
  10. Section 3 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Process Synchronization
  11. Section 3 | Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics
  12. Section 3 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Shortest Path Algos
  13. Section 3 | Theory Of Computation & Compiler Design: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization
  14. Section 3 | Emerging Trends (AI, Societal Ethics & MS Office): Artificial Intelligence, Emerging Tech Trends, Society, Law & Ethics, MS Office Applications
  15. Section 3 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Maintenance and Configuration Management, Software Testing
  16. Section 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  17. Section 3 | OOPS, C++, JAVA, HTML: OOPS with C++, Java, HTML Basics, CSS
  18. Section 3 | Java: Java Fundamentals, Array, String, IO & References
  19. Section 3 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  20. Section 3 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  21. Section 3 | Multimedia: Multimedia
  22. BPSC Previous Year Papers:
  23. BPSC Full Mock 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…