FCFS Scheduling

Duration: 10 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 presents a comprehensive educational session on the First Come First Serve (FCFS) CPU scheduling algorithm, a fundamental topic in operating systems. The instructor begins by defining FCFS as the simplest scheduling algorithm, emphasizing that the process requesting the CPU first is allocated the CPU first. Key characteristics are highlighted on the slide: implementation is managed by a FIFO (First In First Out) queue, and the algorithm is always non-preemptive in nature. The instructor uses a visual analogy of a queue at a ticket counter to reinforce the concept. Following the theoretical introduction, the lecture transitions into a practical numerical problem. A table is displayed listing five processes (P0, P1, P2, P3, P4) with their respective Arrival Times (AT) and Burst Times (BT). The instructor systematically solves the problem by first identifying the process with the earliest arrival time (P2 at time 0) to start the execution. He then constructs a Gantt chart at the bottom of the screen to visualize the sequence of process execution over time. Based on the Gantt chart, he calculates the Completion Time (CT) for each process. Subsequently, he computes the Turn Around Time (TAT) using the formula TAT = CT - AT and the Waiting Time (WT) using the formula WT = TAT - BT. The session concludes with the calculation of the average Turn Around Time and average Waiting Time for the set of processes, providing a complete performance analysis of the FCFS algorithm.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the FCFS algorithm. The slide displays the title 'FCFS (FIRST COME FIRST SERVE)' and bullet points stating it is the simplest scheduling algorithm, managed by a FIFO Queue, and is non-preemptive. The instructor explains that the process requesting the CPU first gets it first, using a background image of a queue to illustrate the concept. He underlines key terms like 'simplest' and 'FIFO Queue' on the slide.

  2. 2:00 – 5:00 02:00-05:00

    The instructor sets up a numerical problem. A table appears with columns for P. No, Arrival Time (AT), and Burst Time (BT). The processes are P0 (AT=2, BT=4), P1 (AT=1, BT=2), P2 (AT=0, BT=3), P3 (AT=4, BT=2), and P4 (AT=3, BT=1). He identifies P2 as the first process because it has the earliest arrival time (0). He draws a Gantt chart, placing P2 from time 0 to 3. He then places P1 (arrived at 1) from 3 to 5, followed by P0 (arrived at 2) from 5 to 9, P4 (arrived at 3) from 9 to 10, and finally P3 (arrived at 4) from 10 to 12. He writes the process names and time intervals on the Gantt chart.

  3. 5:00 – 10:00 05:00-10:00

    The instructor meticulously fills the table with calculated values. For process P2, he calculates Completion Time (CT) as 3, Turn Around Time (TAT) as 3-0=3, and Waiting Time (WT) as 3-3=0. For P1, CT is 5, TAT is 5-1=4, and WT is 4-2=2. For P0, CT is 9, TAT is 9-2=7, and WT is 7-4=3. For P4, CT is 10, TAT is 10-3=7, and WT is 7-1=6. For P3, CT is 12, TAT is 12-4=8, and WT is 8-2=6. He then calculates the averages: Average TAT is (3+4+7+7+8)/5 = 5.8, and Average WT is (0+2+3+6+6)/5 = 3.4. He writes these final calculations at the bottom of the table, showing the summation and division steps.

  4. 10:00 – 10:04 10:00-10:04

    The video concludes with a final view of the completed table and Gantt chart, summarizing the entire solution process for the FCFS scheduling problem. The instructor stands next to the screen, indicating the end of the numerical example.

The lecture provides a clear progression from theoretical definition to practical application. It establishes FCFS as a non-preemptive, FIFO-based algorithm and then immediately demonstrates its execution logic through a step-by-step numerical example. By manually constructing the Gantt chart and deriving performance metrics like Turn Around Time and Waiting Time, the instructor illustrates how arrival times dictate the execution order and how these factors impact overall system efficiency. The final calculation of averages offers a quantitative measure of the algorithm's performance for the given set of processes.

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