SRTF Advantage Vs Disadvantage

Duration: 8 min

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Inside: a video lesson and guided study material.

Module outline

  1. General Intelligence & Reasoning: Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Syllogisms, Venn Diagram, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Data Sufficiency, Puzzle Solving (Puzzles), Data Arrangement, Cubes & Dices, Calendar, Clock, Arithmetic, Number System, HCF LCM, Verbal Analogy (Word Based Analogy), Visual Recognition and Figure Completion, Paper Folding and Cutting, Transformation of Shapes, Clocks and Calendars, Direction Sense, Cubes and Dice, Patterns in Two-Dimensional Figures, Seating Arrangements, Analogy and Classification, Logical Deduction and Induction, Alphabet and Word Tests, Mathematical Operations, Series Completion, Simplification and Approximation, Coding and Decoding, Numerical Reasoning, Assembling and Grouping of Shapes, Three-Dimensional Patterns and Visualization, Vocabulary, Number System, Averages, Mixtures and Alligation, Simple and Compound Interest, Percentages, Algebra, Speed, Time and Distance, Seating and Arrangement Puzzles, Traverse Surveying, Order, Ranking and Sequence, Constraint Puzzles, Syllogisms and Venn Diagrams, Reading Comprehension, Critical Reasoning, Permutations and Combinations, Narrative Sequencing, Project Monitoring, Resources and Safety, Profit, Loss and Discount, Ratio and Proportion, Time and Work, Mensuration, Data Interpretation, Powers, Surds and Logarithms, Sequences and Series, Articles and Determiners, Sentence Completion, Data Sufficiency, Blood Relations, Simple Interest and Compound Interest, Mixture and Alligation, Sequence and Series (Series), Speed Time and Distance, Algebra, Profit and Loss, Powers and Exponents (Surds and Indices), Permutation and Combination
  2. General Awareness: Physics, Chemistry, Biology, History, Geography, Polity, Indian Economy, Environment, Static General Knowledge, GK- Current Affairs, Artificial Intelligence, MS Office Applications, Terms & Abbreviations, Keyboard Shortcuts, Evolution of Indian Banking (Banking & Financial Awareness), Emerging Tech Trends
  3. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus, Probability, Statistics, Signal Space and Optimum Detection, Probability, Statistics
  4. Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep, Number Systems and Codes, Registers and Counters, Boolean Algebra and Logic Gates, Microprocessors and Microcontrollers, Logic Families and CMOS Logic, Microprocessors, Logic Gates and Boolean Algebra, Minimization of Boolean Functions, Timing, Hazards and Testing, Logic Families, Combinational Logic Design, Arithmetic Circuits, Waveform Generators and Timer Circuits, Semiconductor Memories and Programmable Logic Devices, Combinational Logic Circuits, Latches and Flip-Flops, Finite State Machines, Sequential Circuits and State Machines, Minimization of Boolean Functions, Arithmetic Circuits, Latches and Flip-Flops, Number Systems and Codes, Registers and Counters
  5. Computer Organisation & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer, Register Transfer and Microoperations, Semiconductor Memories and Programmable Logic, Processor Organization and Instructions, Memory Hierarchy and Input/Output, Registers and Counters
  6. Programming & Data Structures: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, HTML Basics, OOPS with C++, Java, Object Oriented Technology
  7. Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization
  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  9. 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
  10. 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
  11. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Security, Windows OS, Distributed Systems, Unix OS, Linux OS
  12. Computer Networks: Introduction to CN, 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, Data Communication, Website, Browser & Services, Web Design & Development, Network Security, Cyber Threats and Malware Attacks, Cyber Safety and Security
  13. Full Length Mock Tests:
  14. Sectional Tests:
  15. 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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