Schedulers

Duration: 11 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:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a detailed lecture on the concept of schedulers within Operating Systems, specifically focusing on the different types of schedulers and their roles in process management. The instructor begins by defining schedulers as the mechanism that selects processes from various queues for execution. The lecture progresses to distinguish between Long-term, Short-term, and Medium-term schedulers, explaining their specific functions such as admission control, CPU allocation, and swapping. Visual aids, including diagrams of process states and flowcharts, are used to illustrate how processes migrate between main memory and secondary storage. The session concludes with an explanation of the Dispatcher module, highlighting its critical role in context switching and the concept of dispatch latency.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a slide titled 'Schedulers'. The instructor reads the definition: 'A process migrates among the various scheduling queues throughout its lifetime. The operating system must select, for scheduling purposes, processes from these queues in some fashion. The selection process is carried out by the appropriate scheduler.' He then introduces the 'Types of Schedulers' section. The first type discussed is the 'Long Term Schedulers (LTS)/Spooler'. The slide text explains that in a multiprogramming OS, more processes are submitted than can be executed immediately. Consequently, these processes are 'spooled to a mass-storage device (typically a disk), where they are kept for later execution.' The instructor emphasizes that the long-term scheduler, also called the job scheduler, selects processes from this pool and loads them into memory for execution.

  2. 2:00 – 5:00 02:00-05:00

    The instructor elaborates on the Long Term Scheduler using a hand-drawn diagram. He sketches a box labeled 'M' representing Main Memory and another labeled 'SM' for Secondary Memory, drawing an arrow to show the flow of processes. He explains that the LTS controls the degree of multiprogramming by bringing processes into main memory. He then transitions to the 'Short Term Scheduler (STS)'. The slide text states: 'The short-term scheduler, or CPU scheduler, selects from among the processes that are ready to execute and allocates the CPU to one of them.' The instructor highlights that this scheduler is invoked frequently, unlike the long-term scheduler, to manage CPU allocation efficiently among ready processes.

  3. 5:00 – 10:00 05:00-10:00

    The lecture shifts to the 'Degree of Multiprogramming', defined on the slide as 'The number of processes in memory'. The text notes that the long-term scheduler controls this degree. A key concept presented is stability: 'If the degree of multiprogramming is stable, then the average rate of process creation must be equal to the average departure rate of processes leaving the system.' The instructor draws a graph with 'n' on the y-axis to visualize this stability. He then introduces the 'Medium-term scheduler', explaining its role in swapping. The slide text reads: 'The key idea behind a medium-term scheduler is that sometimes it can be advantageous to remove a process from memory... and thus reduce the degree of multiprogramming.' He explains that this process is called swapping, where a process is swapped out to disk and later swapped back in to continue execution. A diagram shows the flow between 'partially executed swapped-out processes', 'ready queue', 'CPU', and 'I/O'.

  4. 10:00 – 11:14 10:00-11:14

    The final section covers the 'Dispatcher'. The slide defines it as 'the module that gives control of the CPU to the process selected by the short-term scheduler.' The instructor details the functions involved: 'Switching context, switching to user mode, jumping to the proper location in the user program to restart that program.' He stresses that the dispatcher must be fast because it is invoked during every process switch. The concept of 'dispatch latency' is introduced, defined as 'The time it takes for the dispatcher to stop one process and start another running.' The instructor draws a diagram illustrating context switching between two processes to visualize this rapid transfer of control.

The video effectively structures the complex topic of process scheduling by breaking it down into distinct functional modules. It establishes a clear hierarchy starting with the Long-term scheduler for admission, moving to the Short-term scheduler for CPU allocation, and the Medium-term scheduler for memory management via swapping. The lesson culminates with the Dispatcher, the low-level mechanism that executes the actual context switch. This progression helps students understand the lifecycle of a process and the specific OS components responsible for managing its execution state and resource allocation.

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