Multi Level Feedback Queue Scheduling

Duration: 4 min

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Inside: a video lesson and guided study material.

Module outline

  1. HPSC Interview Preparation: Interview Preparation
  2. Python Language: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis, DSA using Python
  3. Data Structure & Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Sorting Algorithms, Minimum Spanning Trees, Time Complexity Analysis, Graph Theory, Shortest Path Algos
  4. Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security
  5. Computer System & Organisation: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer
  6. 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, Transaction Management, Concurrency Control
  7. Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling
  8. Digital Logic & Circuits: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  9. Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Pushdown Automata & CFG, Turing Machines, Moore & Mealy Machines
  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. Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, Data Warehousing & Mining
  12. Introduction to Emerging Trends: Emerging Tech Trends
  13. Digital Society & Cyber Law: Society, Law & Ethics
  14. HPSC PGT Previous Year Paper:
  15. HPSC Assistant Professor Previous Year Paper:
  16. Live Sessions: HPSC Live Sessions, EMRS TGT/PGT Live Class
  17. Full Mock Test:
  18. HPSC PGT - MOCK Test Series:
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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