Worst Fit Policy

Duration: 4 min

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Module outline

  1. Communication Round: Vocabulary, Subject Verb Agreement (Verb Noun Agreement), 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), Direct and Indirect Speech, Active Passive Voice (Voice), Verbal Analogy (Word Based Analogy), Articles, Preposition, Conjunction, Sentence Construction, English Writing Ability, Communication Assessment
  2. Quantitative Aptitude: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Speed Time and Distance, Percentage, Average, Powers and Exponents (Surds and Indices), Time and Work, Mensuration and Geometry, Age Problems, Pipe and Cistern, Probability, Profit and Loss, Simple Interest and Compound Interest, Algebra
  3. Analytical and Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Directions (Direction Test), Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Logical Sequence Of Words, Puzzle Solving (Puzzles), Syllogisms, Seating Arrangements, Calendar, Clock, Blood Relations, Cubes & Dices, Venn Diagram, Analytical Reasoning (Counting Figures Reasoning)
  4. Cognizant Gaming Aptitude: Gamified / Game Based Aptitude
  5. Java (Cluster 1): Java
  6. ANSI SQL MySQL (Cluster 1,2,3): SQL
  7. HTML, CSS, JavaScript (Cluster 1,3): HTML, CSS, JavaScript
  8. Python (Cluster 2): Python for Placements by Yash Sir
  9. Cloud Fundamentals (Cluster 2): Emerging Tech Trends
  10. C# (Cluster 3): C#
  11. OOPs: Object Oriented Programming (OOPS)
  12. Technical Assessment (Coding): Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Pseudo Codes
  13. Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. DBMS: 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
  15. Operating Systems: 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
  16. Computer Networks: 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, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a detailed lecture on memory allocation policies in operating systems, specifically analyzing the Worst Fit and Best Fit strategies. The instructor uses a digital whiteboard to display definitions, advantages, and disadvantages while simultaneously drawing memory diagrams to demonstrate how each policy handles process requests and memory fragmentation. The lesson is structured to compare how different algorithms impact the efficiency of memory usage.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The session begins with the Worst fit policy, defined on the slide as a method that searches the entire memory to allocate the largest partition possible. The instructor draws a horizontal memory block divided into partitions labeled with sizes 8, 5, 30, 20, and 40. He explains that for a process request of size 5, the policy selects the largest available partition, which is 40. He marks this partition with hatching to indicate allocation and calculates the remaining free space as 35 (40 minus 5). The slide text highlights that this policy performs best in variable size partitioning but has a significant disadvantage: it performs worst in fixed size partitioning, resulting in large internal fragmentation because large chunks of memory are used for small processes. He emphasizes that while this leaves a large hole, it might not be useful if the next request is small, but generally, it keeps larger contiguous blocks available.

  2. 2:00 – 4:14 02:00-04:14

    The lecture shifts to the Best fit policy, described on the slide as searching the entire memory to allocate the smallest partition capable of holding the process. The instructor draws a new memory diagram with partitions of sizes 20, 5, 30, and 28. For a request of size 2, he identifies the partition of size 5 as the best fit because it is the smallest partition that can accommodate the request. He allocates the process there, leaving a small remainder of 3. The slide notes that while this performs best in fixed size partitioning, it is difficult to implement and performs worst in variable size partitioning because the remaining spaces are often very small and unusable, leading to external fragmentation. The video concludes with a brief mention of Next fit policy as a modification of best fit where searching starts from the current position rather than the beginning, aiming to reduce search time.

The video effectively contrasts Worst Fit and Best Fit policies by defining their search strategies and illustrating their impact on memory fragmentation through concrete numerical examples. It highlights the trade-off between leaving large holes (Worst Fit) and minimizing wasted space at the cost of creating unusable fragments (Best Fit).

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