External Fragmentation

Duration: 5 min

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Module outline

  1. Quantitative Aptitude: Ratio and Proportion (Ratios), Data Interpretation, Mixture and Alligation, Permutation and Combination, Number System, Sequence and Series (Series), Speed Time and Distance, Speed Mathematics and Basic Mathematics, Algebra, Percentage, Profit and Loss, Simple Interest and Compound Interest, Powers and Exponents (Surds and Indices), Time and Work, Mensuration and Geometry, Partnership
  2. Reasoning Ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Seating Arrangements, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Directions (Direction Test), Ranking, Order and Sequence, Syllogisms, Blood Relations, Puzzle Solving (Puzzles), Inequality, Machine Input-Output
  3. English Language: Vocabulary, Noun, Subject Verb Agreement (Verb Noun Agreement), Adjectives, 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), Sentence Construction, Pronoun, Preposition, Conjunction, Adverb, Verb, Modals, Articles, Determiner, Interjection
  4. General Awareness: Evolution of Indian Banking (Banking & Financial Awareness), GK- Current Affairs, Static General Knowledge, Indian Economy
  5. C Concepts + MCQs (IT Specialist): C Programming by Yash Sir, C Language Core
  6. Java (IT Specialist): Java
  7. Python (IT Specialist): Python for Placements by Yash Sir, Python Basics
  8. OOPs (IT Specialist): Object Oriented Programming (OOPS)
  9. DBMS (IT Specialist): 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
  10. SQL (IT Specialist): SQL
  11. Software Engineering (IT Specialist): Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Data Structure (IT Specialist): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  13. Operating System (IT Specialist): 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
  14. Compiler Design (IT Specialist): 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
  15. Computer Architecture (IT Specialist): Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations, Multiprocessors, Programming the Basic Computer
  16. Data Communication & Networking (IT Specialist): 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
  17. Descriptive Test (Main Exam): English Writing Ability
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture provides a comprehensive explanation of external fragmentation within the context of operating system memory management. The instructor defines external fragmentation as a condition arising from contiguous allocation policies where the total available memory space is sufficient to satisfy a process request, but the space is not contiguous, making allocation impossible. This results in significant memory wastage. The lesson progresses from the theoretical definition displayed on the screen to a practical visual demonstration using a memory block diagram. The instructor draws a memory region with a central allocated section and free blocks on either side, labeling them to show the distribution of free space. He uses specific numerical examples to illustrate why a process cannot be loaded even when the aggregate free memory exceeds the process size, highlighting the critical limitation of contiguous allocation.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by displaying the definition of external fragmentation on the screen, stating it is a function of contiguous allocation policy. The text explicitly notes that space requested by a process might be available in memory but cannot be allocated if it is not contiguous. To visualize this, he draws a long horizontal rectangle representing a memory block. He shades a central portion of this rectangle with diagonal lines to represent an allocated region. He then writes the number '5' above the free blocks on the left and right sides of the allocated region, indicating the size of the available free space in those specific segments. This setup establishes the scenario where free memory exists but is fragmented, preventing a single large allocation.

  2. 2:00 – 4:55 02:00-04:55

    The instructor continues the explanation by introducing specific process sizes to test against the memory diagram. He writes the number '7' and '12' below the diagram to represent the size of incoming processes. He explains that a process requiring 7 units of memory cannot be allocated because the available free blocks are only 5 units each, even though their sum is 10. He briefly displays a photograph of a large family with the caption 'on Family Are Expecting Their 17th Child' as a humorous interlude or analogy. He returns to the diagram, writing '9' as another example, reinforcing that the lack of a single contiguous block of sufficient size prevents allocation. He concludes that this inability to utilize available free space due to non-contiguity is the essence of external fragmentation, emphasizing the wastage involved.

The lecture effectively bridges the gap between the abstract definition of external fragmentation and its practical implications in memory management. By using a simple visual model of memory blocks and specific numerical examples, the instructor clarifies why total free memory is not the only factor in allocation decisions. The key takeaway is that contiguous allocation policies suffer from this wastage when free space is scattered, preventing the loading of processes that could theoretically fit in the total available memory. This distinction is crucial for understanding memory management strategies.

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