LRTF

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 lecture covers CPU scheduling algorithms, specifically Longest Job First (LJF) and its pre-emptive variant, Longest Remaining Time First (LRTF). The instructor defines LJF, noting on-screen text that "Process having longest Burst Time will get scheduled first." He demonstrates a non-preemptive example using a table of five processes (P1-P5) with varying arrival and burst times. He constructs a Gantt chart, showing how P1 runs first, followed by P4, P5, P3, and finally P2, based on the longest available burst time. The second half introduces LRTF, emphasizing its pre-emptive nature where the process with the longest *remaining* time is chosen, even if it was already running.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the Longest Job First algorithm, highlighting on-screen text that states "Process having longest Burst Time will get scheduled first." He presents a table with five processes (P1-P5) and their Arrival/Burst Times. He then draws a timeline (Gantt chart) to solve a non-preemptive example. He starts with P1 at time 0, runs it for 3 units (finishing at t=3). At t=3, he compares available processes P2 (BT=2), P3 (BT=4), and P4 (BT=5), selecting P4 because it has the longest burst time. He continues this logic, selecting P5 (BT=6) which runs from t=8 to t=14, then P3 (BT=4) from t=14 to t=18, and finally P2 (BT=2) from t=18 to t=20.

  2. 2:00 – 3:42 02:00-03:42

    The topic shifts to Longest Remaining Time First (LRTF), described as pre-emptive. A table shows three processes (P1-P3) arriving at time 0 with burst times 2, 4, and 8. The instructor draws a Gantt chart showing P3 running initially. He updates the remaining burst times in the table (crossing out original values and writing new ones, e.g., P3's BT changes from 8 to 4). He demonstrates preemption by switching between P3 and P2 as their remaining times fluctuate. At time 8, when remaining times for P1, P2, and P3 are all equal (2 units), he switches to P1, then P2, then P3, finishing the schedule at time 11. This illustrates how LRTF handles ties and preemption dynamically.

The lecture distinguishes between non-preemptive and pre-emptive scheduling based on job length. LJF minimizes average waiting time but can cause starvation for short jobs. LRTF adds pre-emption, allowing shorter jobs to run if their remaining time becomes the longest relative to others, though the example shows frequent context switching. Both algorithms prioritize longer tasks, contrasting with Shortest Job First. The visual Gantt charts and table updates provide clear evidence of the scheduling logic.

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