Best Fit Policy

Duration: 5 min

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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
  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
  18. Paper 2 | Full Length Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The lecture provides a detailed explanation of the "Best fit policy" used in operating system memory management. The instructor defines the policy as a strategy where the system searches the entire available memory to locate and allocate the smallest partition that is large enough to hold the incoming process. He contrasts this with other policies by highlighting its specific advantages and disadvantages. The core takeaway is that while Best Fit minimizes wasted space in fixed-size partitioning, it is computationally expensive and leads to severe external fragmentation in variable-size partitioning schemes due to the creation of many tiny, unusable memory holes.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The session begins with the instructor standing next to a slide titled "Best fit policy." The slide text explicitly defines the method: "Here, we search the entire memory and will allocate the smallest partition which is capable enough." The instructor elaborates on the bullet points. He points to the "Advantage" section, stating the policy "perform[s] best in fix size partitioning scheme." He then moves to the "Disadvantage" section, noting it is "difficult to implement" and "perform[s] worst in variable size partitioning as the remaining spaces which are of very small size." Towards the end, he prepares to draw a diagram on the whiteboard area below the text.

  2. 2:00 – 5:00 02:00-05:00

    The instructor demonstrates the Best Fit algorithm using a visual memory map. He draws a long rectangle representing memory and writes numbers above it: 8, 5, 20, 25, and 40, representing available partition sizes. He introduces a process request of size 23, which he circles. He explains that the algorithm scans the list and selects the partition of size 25 because it is the smallest one that can accommodate the 23-unit process. He shades the 25-block with diagonal lines to indicate it is now allocated. He points out that 2 units of space remain (25 - 23 = 2), creating a small fragment. He then draws a second, more complex diagram above the first one to show a scenario with partitions 20, 2, 5, and 30, illustrating how fragmentation accumulates over time.

  3. 5:00 – 5:17 05:00-05:17

    In the final moments, the instructor focuses on the second diagram he drew. He points specifically to the partition of size 30 and the small gap of size 2 next to it. He has written a circled "28" indicating a process size. He uses this visual to reinforce the concept of external fragmentation. He explains that even though there is free space available in the memory (the 20, 2, and 5 blocks), it might not be contiguous enough to satisfy a large request, demonstrating why the policy performs poorly in variable-size partitioning. He concludes the segment by gesturing towards the fragmented blocks to emphasize the inefficiency.

The video successfully bridges the gap between theoretical definitions and practical memory management issues. By starting with the slide text and moving to a hand-drawn diagram, the instructor makes the abstract concept of "Best Fit" concrete. The progression from defining the policy to showing the specific calculation (25 - 23 = 2) and then illustrating the long-term consequence (fragmentation) provides a comprehensive understanding. The visual cues of shading allocated blocks and circling process sizes are crucial for students to follow the logic of the algorithm.

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