Look Scheduling

Duration: 3 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.

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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