Multi Level Feedback Queue Scheduling

Duration: 4 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 provides a detailed lecture on the Multi-level Feedback Queue Scheduling algorithm used in operating systems. The instructor begins by distinguishing this flexible approach from the rigid multilevel queue scheduling, where processes are permanently assigned to specific queues. He explains that the feedback mechanism allows processes to migrate between priority levels based on their CPU burst characteristics, ensuring that interactive and I/O-bound processes receive higher priority while CPU-bound processes are demoted. The lecture concludes with a specific numerical example illustrating time quanta and queue transitions.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the topic using a slide titled Multi-level Feedback Queue Scheduling. He contrasts this with standard multilevel queues, noting on-screen text that says: Normally, when the multilevel queue scheduling algorithm is used, processes are permanently assigned to a queue when they enter the system. He explains that unlike this inflexible setup, the feedback queue allows processes to move between queues. The slide text further clarifies: The multilevel feedback queue scheduling algorithm, in contrast, allows a process to move between queues. He details that processes using too much CPU time are moved to lower-priority queues, whereas I/O-bound and interactive processes remain in higher-priority queues. He also mentions that a process waiting too long in a lower-priority queue may be moved to a higher-priority queue to prevent starvation, a concept known as aging.

  2. 2:00 – 3:48 02:00-03:48

    The lecture shifts to a concrete example with a diagram on the right side of the slide. The text reads: A process entering the ready queue is put in queue 0. A process in queue 0 is given a time quantum of 8 milliseconds. The instructor points to the diagram, which shows three stacked boxes labeled quantum = 8, quantum = 16, and FCFS. He explains that if a process does not finish within 8 milliseconds, it is moved to the tail of queue 1. If it still isn't complete after 16 milliseconds in queue 1, it is preempted and put into queue 2. He draws arrows on the screen to visualize this flow, emphasizing that processes needing more than 8 but less than 24 milliseconds are served quickly with lower priority, while long processes automatically sink to queue 2 and are served in FCFS order.

The video effectively bridges theory and practice. It starts by defining the core advantage of feedback queues—flexibility and starvation prevention—before grounding the concept in a specific algorithm with defined time quanta. This progression helps students understand both the why and the how of the scheduling mechanism.

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