First Come First Serve Scheduling

Duration: 6 min

This video lesson is available to enrolled students.

Return to /learn/UP-LT-GRADE-ASSISTANT-TEACHER-2025/cs-06-operating-system/disc-scheduling/fcfs-sstf-scheduling/asset-first-come-first-serve-scheduling after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. CS | 01 | Digital Logic and Circuits and Discrete Mathematical Structures: Digital Systems & Boolean Basics, Number System, Number Representation, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Permutation and Combination
  3. CS | 02 | Computer Organization and Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Multiprocessors
  4. CS | 03 | Data Structures and Algorithm: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Complexity Theory, Advanced Algorithms
  5. CS | 04 | Problem Solving through C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  6. CS | 05 | Object Oriented Techniques: Object Oriented Technology, Java
  7. CS | 06 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Unix OS
  8. CS | 07 | Database Management Systems: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization, Query Processing & Optimization, File Organization & Indexing
  9. CS | 08 | 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
  10. CS | 09 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  11. CS | 10 | Internet Technology, Web Design and Web Technology: Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, JavaScript-Basics, HTML Basics
  12. CS | 11 | System Analysis And Design: Fundamentals of Systems and Information Systems, SDLC and Development Approaches, Software Documentation and Software Requirements Specification (SRS), SDD and Quality Assurance, Security, Risk Management & Maintenance
  13. CS | 12 | Information Security and Cyber Laws: Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Electronic Data Interchange and E-Commerce, Physical Security and Cryptography Basics, Intrusion Detection Systems (IDS), Cyber Safety and Security
  14. CS | 13 | Computer Graphics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing
  15. GS Paper | 01 | Indian and World Geography: Geography
  16. GS Paper | 02 | History: History
  17. GS Paper | 03 | Indian Economy & Social Development: Indian Economy
  18. GS Paper | 04 | General Science: Biology, Chemistry, वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research
  19. GS Paper | 05 | Elementary Maths: संख्या पद्धति / Number System, Divisibility Rules, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, प्रतिशत / Percentage, लाभ, हानि और बट्टा / Profit, Loss and Discount, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, अनुपात और समानुपात / Ratio and Proportion, औसत / Average, समय और कार्य / Time and Work, समय, चाल और दूरी / Time, Speed and Distance, Algebra, घन क्षेत्रमिति / Solid Mensuration, आँकड़ा निर्वचन / Data Interpretation, Arithmetic, Statistics, Probability, Sequence and Series (Series), मिश्रण और एलिगेशन / Mixture and Alligation, Calculus, Trigonometry, Vectors, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, यूक्लिडीय ज्यामिति और क्षेत्रमिति / Euclidean Geometry and Mensuration, सांख्यिकी और प्रायिकता / Statistics and Probability, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers, समतल क्षेत्रमिति / Plane Mensuration, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics
  20. GS Paper | 06 | Indian Polity and Governance: Polity
  21. GS Paper | 07 | Current Events: समसामयिकी / Current Affairs
  22. UPLT Live Classes Notes: UPLT Live Classes
  23. UPLT Full Mock Tests Tier 1:
  24. UPLT Full Mock Tests Tier 2:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video lecture focuses on the First Come First Serve (FCFS) disk scheduling algorithm, a fundamental concept in operating systems. The instructor begins by defining FCFS as the simplest form of disk scheduling where requests are serviced strictly in the order they arrive in the queue. He emphasizes that while the algorithm is intrinsically fair and prevents starvation, it generally fails to provide the fastest service because it does not optimize seek time. The lecture transitions into a practical demonstration where the instructor writes a sequence of cylinder numbers on the whiteboard and uses a hand-drawn diagram of a disk to visualize the head movements, illustrating the inefficiencies of the algorithm through a concrete numerical example.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the topic using a presentation slide titled FCFS (First Come First Serve). The slide text explicitly states, The simplest form of disk scheduling is, of course, the first-come, first-served (FCFS) algorithm. He reads and explains the advantages listed on the slide, such as Easy to understand easy to use and Every request gets a fair chance. He also points out the disadvantage that it Does not try to optimize seek time (extra seek movements). The instructor notes that while there is no starvation, the system may suffer from convoy effect. He begins to draw a large circle on the right side of the screen to represent the disk platter.

  2. 2:00 – 5:00 02:00-05:00

    The instructor sets up a specific numerical example to calculate seek time. He writes a sequence of numbers on the board: 50, 27, 71, 97, 3, 54. He circles the first number, 50, indicating the initial head position. He explains that the head must move from 50 to 27, then to 71, and so on, following the arrival order. He writes the calculation |50 - 27| to demonstrate how the distance is found. He draws concentric circles on the disk diagram to represent different cylinders. He draws arrows on the diagram to show the head moving from the outer tracks to inner tracks and back, visually demonstrating the extra seek movements mentioned in the disadvantages.

  3. 5:00 – 5:42 05:00-05:42

    The instructor continues the calculation, summing up the individual seek times to find the total. He writes T.T = ... on the board and lists the absolute differences like |50 - 27| and |71 - 27|. He points to the diagram, tracing the path of the disk head as it jumps between cylinders 50, 27, 71, 97, 3, and 54. He emphasizes that this back-and-forth movement is inefficient compared to other algorithms. He concludes the segment by reiterating that while FCFS is simple and fair, the lack of optimization leads to longer wait times for processes, validating the convoy effect mentioned earlier.

The video effectively bridges theory and practice. It starts with a clear definition and a list of pros and cons from a slide, establishing the theoretical framework. It then moves to a hands-on example where the instructor writes down specific numbers and draws a diagram, making the abstract concept of seek time concrete. The progression from reading the slide to calculating |50 - 27| and drawing the disk path helps students visualize why FCFS is considered inefficient despite its fairness.

Loading lesson…