Pre-emptive Priority Scheduling

Duration: 6 min

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Module outline

  1. Communication Round: Vocabulary, Subject Verb Agreement (Verb Noun Agreement), Tenses, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Direct and Indirect Speech, Active Passive Voice (Voice), Verbal Analogy (Word Based Analogy), Articles, Preposition, Conjunction, Sentence Construction, English Writing Ability, Communication Assessment
  2. Quantitative Aptitude: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Speed Time and Distance, Percentage, Average, Powers and Exponents (Surds and Indices), Time and Work, Mensuration and Geometry, Age Problems, Pipe and Cistern, Probability, Profit and Loss, Simple Interest and Compound Interest, Algebra
  3. Analytical and Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Directions (Direction Test), Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Logical Sequence Of Words, Puzzle Solving (Puzzles), Syllogisms, Seating Arrangements, Calendar, Clock, Blood Relations, Cubes & Dices, Venn Diagram, Analytical Reasoning (Counting Figures Reasoning)
  4. Cognizant Gaming Aptitude: Gamified / Game Based Aptitude
  5. Java (Cluster 1): Java
  6. ANSI SQL MySQL (Cluster 1,2,3): SQL
  7. HTML, CSS, JavaScript (Cluster 1,3): HTML, CSS, JavaScript
  8. Python (Cluster 2): Python for Placements by Yash Sir
  9. Cloud Fundamentals (Cluster 2): Emerging Tech Trends
  10. C# (Cluster 3): C#
  11. OOPs: Object Oriented Programming (OOPS)
  12. Technical Assessment (Coding): Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Pseudo Codes
  13. Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. DBMS: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  15. Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  16. Computer Networks: 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, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video explains the Pre-emptive Priority Scheduling algorithm in Operating Systems. The lecturer defines the concept where a higher priority process interrupts a running lower priority process, causing a context switch. He then solves a numerical problem involving six processes (P0-P5) with specific Arrival Times, Burst Times, and Priorities. The solution involves constructing a Gantt chart to determine execution order and calculating Completion Time (CT), Turnaround Time (TAT), and Waiting Time (WT) for each process.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The lecturer introduces the concept of Priority Scheduling, specifically the pre-emptive variant. He explains that once a decision is made, the process with the highest priority is scheduled on the CPU. Crucially, he notes that if a new process enters the system with a priority higher than the currently running process, a context switch occurs, and the processor is immediately provided to the new high-priority process. This establishes the core mechanism of pre-emption where higher priority tasks interrupt lower priority ones.

  2. 2:00 – 5:00 02:00-05:00

    The lecture transitions to a numerical problem involving six processes: P0 through P5. A table is displayed showing Arrival Time (AT), Burst Time (BT), and Priority for each. The lecturer begins constructing a Gantt chart to visualize the execution order. He analyzes the arrival times, noting P0 arrives at time 1, while P1 and P2 arrive at time 2. He identifies P3 as having the highest priority (8), marked as 'H' on the board. He starts drawing the timeline, marking the initial idle period and the entry of processes, preparing to determine which process runs next based on the priority rules.

  3. 5:00 – 6:30 05:00-06:30

    The lecturer completes the Gantt chart and fills in the calculation table. He determines the Completion Time (CT) for each process based on the execution order derived from the Gantt chart. For instance, P3 completes at time 8. He then calculates Turnaround Time (TAT) using the formula TAT = CT - AT and Waiting Time (WT) using WT = TAT - BT. He fills the columns with specific values, such as P0 having a CT of 18 and a WT of 13, while P3 has a WT of 0. The video concludes with the table fully populated, ready for the final average calculation.

The video provides a comprehensive guide to Pre-emptive Priority Scheduling. It starts with the theoretical definition, emphasizing the context switch mechanism when higher priority processes arrive. It then applies this theory to a concrete example, demonstrating how to manage multiple processes with varying arrival and burst times. The step-by-step construction of the Gantt chart and the subsequent calculation of performance metrics like TAT and WT offer a clear method for solving such operating system problems.

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