Look Scheduling

Duration: 3 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 1 | General Studies: State Wise GK
  3. Paper 1 | Information and Communication Technology: Role of Internet and Web Services, Security in Mobile and Wireless Computing
  4. Paper 1 | Current Affairs: GK- Current Affairs
  5. Paper 2 | Discrete Mathematical Structure: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Probability
  6. Paper 2 | Digital Computer Organization And Architecture: Number System, Number Representation, Sequential Circuits, Combinational Circuit, Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer
  7. Paper 2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  8. Paper 2 | Programming Languages & Object-Oriented Programming Concepts: Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
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  10. Paper 2 | Data Structure And Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Advanced Algorithms
  11. Paper 2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS
  12. Paper 2 | 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
  13. Paper 2 | 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
  14. Paper 2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization, Enhanced Data Models
  15. Paper 2 | Computer Network And Information Security: Introduction to CN, Data Communication, Application Layer, Hardware basics, Cyber Threats and Malware Attacks, Network Security, 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
  16. Paper 2 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  17. Paper 2 | Current Trends & Technologies: Emerging Tech Trends, Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Fuzzy Sets, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms, Artificial Intelligence, Data Warehousing & Mining, Electronic Data Interchange and E-Commerce, Terms & Abbreviations
  18. Paper 2 | Full Length Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture provides a detailed explanation of the LOOK disk scheduling algorithm, a specific variation of the SCAN algorithm used in operating systems for managing disk I/O requests. The instructor begins by defining LOOK, noting that it differs from SCAN because the disk arm does not travel to the physical end of the disk. Instead, it moves only to the last request in the current direction before reversing. The lecture covers the pros and cons, listing advantages such as "Better performance compared to SCAN" and disadvantages like the "Overhead to find the last request." Visual aids include a slide with text definitions and a hand-drawn diagram illustrating the disk arm movement to clarify the concept for students.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces LOOK Scheduling by comparing it directly to the SCAN algorithm. The slide text explicitly states, "It is similar to the SCAN disk scheduling algorithm except the difference that the disk arm in spite of going to the end of the disk goes only to the last request to be serviced in front of the head." He then lists specific advantages on the slide, such as "Better performance compared to SCAN" and "Should be used in case of less load." Conversely, he highlights disadvantages including "Overhead to find the last request" and "Should not be used in case of more load." To visualize the relationship between algorithms, he draws a tree diagram on the whiteboard, writing "SCAN" at the top and branching to "C-SCAN" and "LOOK," crossing out C-SCAN to focus the lesson on LOOK.

  2. 2:00 – 3:21 02:00-03:21

    The instructor illustrates the concept with a diagram to clarify the movement logic. He draws a large circle representing the disk and a line inside to show the arm's path. He writes "LOOK" next to the circle. He explains that the arm reverses direction from the last request, preventing "unnecessary traversal to the end of the disk." He uses hand gestures to demonstrate the back-and-forth motion of the disk head, emphasizing that it doesn't go to the physical end like SCAN does. He points to the text "Should be used in case of less load" to reinforce the context of usage. He also draws a squiggly line inside the circle to represent the requests being serviced, showing how the arm moves back and forth between them without reaching the outer edge of the disk.

The lesson effectively contrasts LOOK with SCAN by highlighting the efficiency gain of not traversing to the disk's physical end. The instructor uses both textual definitions and visual diagrams to clarify the movement logic, emphasizing that LOOK is suitable for lighter loads due to the overhead of finding the last request. The visual progression from text to diagram helps students understand the practical application of the algorithm in disk scheduling scenarios.

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