First Fit Policy

Duration: 6 min

This video lesson is available to enrolled students.

Return to /learn/RSSB-SENIOR-COMPUTER-INSTRUCTOR/operating-systems/memory-management/contiguous-allocation/asset-first-fit-policy after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Mensuration and Geometry, Age Problems, Arithmetic, Statistics, Probability, Profit and Loss, Simple Interest and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, Powers and Exponents (Surds and Indices), Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy
  3. Paper-1 & 2 | Data Interpretation: Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Analogy, Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Data Arrangement, Logical Sequence Of Words, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: Selection Decision Table (Decision Making)
  7. Paper-1 | General Science: Physics, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: State Wise GK, GK- Current Affairs
  9. Paper-2 | Fundamentals of Computer: Basics of COA, Number System, Floating Point Rep, Number Representation
  10. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits
  11. Paper-2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Linux OS, Distributed Systems
  12. 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, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  13. Paper-2 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  15. Paper 2 | Oops, C++, Java: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  16. 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
  17. Paper 2 | Emerging Trends and AI: Emerging Tech Trends, Artificial Intelligence
  18. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Advanced Algorithms
  19. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, 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, Ethical Hacking
  20. Paper-2 I Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  21. Paper-2 | Computer Organization and Architecture: Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations
  22. Paper-2 | Web Development: JavaScript-Basics, HTML Basics, CSS, XML
  23. Pedagogy: Child Development, Concept of Pedagogy, Psychology, Theories, Inclusive Education, Experiential Pedagogy, Curriculum Framework & Reforms, National Education Policy (NEP) 2020
  24. Live Sessions: RSSB Live Sessions
  25. RSSB Paper 1 - Full Mock Tests:
  26. RSSB Paper 2 - Full Mock Tests:
  27. SCI Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture provides a detailed explanation of memory allocation strategies in operating systems, focusing primarily on the "First fit" policy before briefly introducing the "Best fit" policy. The instructor starts by defining First fit policy, stating on the slide that it involves searching memory from the base and allocating the first partition that is capable enough. He lists the advantages as being simple, easy to use, and easy to understand. Conversely, he notes the disadvantage is poor performance in terms of both time and space. To illustrate this, he draws a memory diagram with partitions of sizes 15, 16, and 30. He demonstrates the allocation of a process of size 5 to the first partition. The lecture then transitions to the Best fit policy, defining it as searching the entire memory to find the smallest capable partition. He notes its advantage in fixed-size partitioning but highlights its disadvantage in variable-size partitioning due to the creation of very small remaining spaces.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the "First fit policy" using a slide that defines it as searching memory from the base to allocate the first capable partition. The slide text explicitly states: "as the name implies, it states searching the memory from the base and will allocate first partition which is capable enough." He lists advantages like being simple, easy to use, and easy to understand. Conversely, he notes the disadvantage is poor performance in terms of both time and space. He begins a visual demonstration by drawing a memory block and marking partitions with sizes 15, 16, and 30. He writes "5" with an arrow pointing to the first partition, indicating a process of size 5 is arriving. He allocates it to the first partition of size 15, leaving 10 units of space.

  2. 2:00 – 5:00 02:00-05:00

    The instructor continues the First fit example, allocating a process of size 10 to the remaining space in the first partition. He then allocates a process of size 12 to the second partition (size 16) and a process of size 30 to the third partition (size 30). He draws a second diagram below to further illustrate the concept, writing numbers like 4, 4, 15, 12, and 30 to represent different partition sizes or process requests. He emphasizes the sequential nature of the search, moving from the base of memory upwards. He circles a number '2' and points to the partitions, explaining how the allocation happens sequentially. He draws hatching lines to indicate allocated memory. He gestures with his hand to show the flow of allocation.

  3. 5:00 – 6:04 05:00-06:04

    The slide transitions to the "Best fit policy". The text explains that this policy searches the entire memory to allocate the smallest partition capable of holding the process. The instructor points out that while it performs best in fixed-size partitioning, it is difficult to implement and performs worst in variable-size partitioning due to the creation of very small remaining spaces. The video ends as he begins to explain this new concept, standing next to the slide which lists the advantages and disadvantages clearly. The slide text reads: "Here, we search the entire memory and will allocate the smallest partition which is capable enough."

The lecture effectively contrasts two memory allocation strategies. First fit is presented as a quick, simple method that might lead to fragmentation, while Best fit is shown as a more precise but computationally expensive method that can lead to external fragmentation. The visual diagrams help clarify how processes are mapped to memory blocks in each scenario. The instructor uses specific numerical examples to make the abstract concepts concrete for the students. The transition from First fit to Best fit highlights the trade-off between speed and efficiency in memory management. Understanding these policies is crucial for optimizing system performance.

Loading lesson…