First Fit Policy

Duration: 6 min

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Module outline

  1. About Course: UPPSC Course Overview
  2. Interview Preparation & Guidance: Interview Preparation
  3. Paper 1 | General Hindi: भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, वर्णमाला, समास, संधि, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material)
  4. Paper 2 | General Studies: State Wise GK, Polity, Geography, History, GK- Current Affairs
  5. Paper 1 | Programming Language: Language Design, C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, OOPS with C++
  6. Paper 1 | Database Management Systems: 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, ORDBMS, NoSQL
  7. Paper 1 | Cyber Security: Society, Law & Ethics, Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Electronic Data Interchange and E-Commerce, Physical Security and Cryptography Basics, Intrusion Detection Systems (IDS), Cyber Safety and Security, Ethical Hacking
  8. Paper 1 | Computer Organization and Architecture: Basics of COA, Programming the Basic Computer, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design
  9. Paper 1 | 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
  10. Paper 1 | Design and Analysis of Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  11. Paper 1 | Data Structures: Introduction to DS, Array, Linked List, Stack, Queue, Tree, Graphs, Hashing
  12. Paper 1 | Discrete Structures and Theory of Logic: Permutation and Combination, Set Theory, Relations, Functions, Propositional and Predicate Logic, Graph Theory, Group Theory
  13. Paper 1 | Software Project Management: Software Project Management
  14. Paper 2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS, Linux OS, Security
  15. 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, Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Pushdown Automata & CFG, Complexity Theory
  16. Paper 2 | Artificial Intelligence & High Performance Computing: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Natural Language Processing, Emerging Tech Trends
  17. Paper 2 | Image Processing: Digital Image Fundamentals, Image Enhancement, Image Restoration, Color Image Processing, Image Compression
  18. 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
  19. Paper 2 | Computer Graphics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing
  20. Paper 2 | Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, Java
  21. Paper 2 | Soft Computing: Fuzzy Sets, Artificial Neural Networks, Genetic Algorithms
  22. Paper 2 | Distributed System: Distributed Systems
  23. UPPSC Live Class Recordings: UPPSC Polytechnic Lecturer 2025 (CS)
  24. Previous Year Papers:
  25. Mock Test:
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.

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