SRTF Advantage Vs Disadvantage

Duration: 8 min

This video lesson is available to enrolled students.

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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, प्रतिशतता / Percentage, अनुपात, समानुपात, साझेदारी एवं मिश्रण / Ratio, Proportion, Partnership and Mixtures, औसत / Averages, आँकड़ा विश्लेषण एवं शोध सांख्यिकी / Data Analysis and Statistics in Research, क्रमचय, संचय एवं प्रायिकता / Permutation, Combination and Probability, श्रेणी / Series, आँकड़े एवं आलेखीय निरूपण / Data and Graphical Representation, आँकड़ा निर्वचन: तालिका / Data Interpretation: Tables
  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
  9. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  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, कंप्यूटर की मूल बातें और हार्डवेयर / Computer Fundamentals and Hardware, पारितंत्र और जैव विविधता / Ecosystems and Biodiversity, मेमोरी, भंडारण और डेटा निरूपण / Memory, Storage and Data Representation, कंप्यूटर सॉफ्टवेयर / Computer Software, निरुपाधिक प्रतिज्ञप्तियाँ / Categorical Propositions, ऑफिस अनुप्रयोग / Office Applications, संकेत विज्ञान एवं अर्थ / Semiotics and Meaning, मल्टीमीडिया और फ़ाइल प्रारूप / Multimedia and File Formats, कंप्यूटर नेटवर्क / Computer Networks, संचार की बाधाएँ / Barriers to Communication, उच्च शिक्षा संस्थानों के प्रकार / Types of Higher Education Institutions, इंटरनेट और वर्ल्ड वाइड वेब / Internet and World Wide Web, ई-मेल और ऑनलाइन संचार / Email and Online Communication, शिक्षण विधियाँ / Methods of Teaching, साइबर सुरक्षा / Cyber Security, डिजिटल नैतिकता, बौद्धिक संपदा और समाज / Digital Ethics, IPR and Society, शोध-प्रबंध एवं लेख लेखन / Thesis and Article Writing, डिजिटल एवं नव माध्यम / Digital and New Media, क्लाउड और वितरित कंप्यूटिंग / Cloud and Distributed Computing, उभरती प्रौद्योगिकियाँ / Emerging Technologies, प्राकृतिक प्रकोप और आपदा प्रबंधन / Natural Hazards and Disaster Management, शिक्षा और शासन में ICT / ICT in Education and Governance
  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 analysis of the Shortest Job First (SJF) CPU scheduling algorithm, focusing on its pros and cons. The instructor begins by establishing the theoretical superiority of the pre-emptive version, noting it guarantees minimal average waiting time and is often called the "optimal algorithm." He explains that it sets a standard for other algorithms and provides better response times than FCFS. The lecture then shifts to the critical disadvantages, highlighting that the algorithm is practically unimplementable because the system cannot predict the length of the next CPU burst. This limitation causes "starvation," where long processes wait indefinitely. The instructor uses a visual analogy of a busy street food stall to illustrate how longer processes suffer from poor response times and starvation.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor focuses on the "Advantage" slide. He reads and underlines the first point: "Pre-emptive version guarantees minimal average waiting time so some time also referred as optimal algorithm." He emphasizes that "Pre-emptive version" is key here. He explains that because it minimizes waiting time, it is mathematically optimal. He then moves to the second point, "Provide a standard for other algo in terms of average waiting time," underlining "Provide a standard." He explains that other algorithms are judged against SJF's performance. Finally, he discusses the third point, "Provide better average response time compare to FCFS," underlining "Provide better average response time." He contrasts this with FCFS, where a long process at the front can delay short processes.

  2. 2:00 – 5:00 02:00-05:00

    The slide changes to "Disadvantage." The instructor underlines the first point: "This algo cannot be implemented as there is no way to know the length of the next CPU burst." He stresses that "cannot be implemented" is the core issue. The second point states, "Here process with the longer CPU burst requirement goes into starvation." He underlines "longer CPU burst requirement" and circles "starvation." The third point reads, "No idea of priority, longer process has poor response time." He underlines "No idea of priority." An image of a street vendor serving customers is displayed, which he uses as a visual aid to explain the concept of waiting lines and how some people (processes) might wait much longer than others.

  3. 5:00 – 7:55 05:00-07:55

    The instructor elaborates on the starvation problem using the visual analogy. He explains that if short processes keep arriving, the long process at the back of the queue never gets served. He circles "starvation" again to reinforce the concept. He discusses the third point, "No idea of priority," explaining that without priority, a long process has poor response time. He mentions that this is why pure SJF is not used; instead, approximations are made. He gestures towards the image of the food stall, comparing the customers waiting for food to processes waiting for the CPU. He concludes that while SJF is theoretically optimal, its practical implementation is flawed due to the unpredictability of CPU bursts.

The lecture bridges the gap between theory and practice for SJF. It confirms the algorithm's theoretical optimality for waiting time but clearly identifies the fatal flaw of unimplementability due to unknown burst lengths. This leads to the critical issue of starvation, where long processes are neglected. The visual analogy of the food stall effectively grounds the abstract concept of starvation in a relatable real-world scenario, helping students understand why priority scheduling or aging techniques are necessary in real operating systems.

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