Linux Memory Allocation

Duration: 21 min

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Inside: a video lesson and guided study material.

Module outline

  1. Course Overview: About the Course
  2. Paper - 1 | Unit - 1 | Teaching Aptitude: Concept and Objectives of Teaching / शिक्षण की अवधारणा एवं उद्देश्य, Levels of Teaching / शिक्षण के स्तर, Learner's Characteristics / शिक्षार्थी की विशेषताएँ, Learning: Nature and Theories / अधिगम: प्रकृति एवं सिद्धांत, Cognition, Memory and Metacognition / संज्ञान, स्मृति एवं अधिसंज्ञान, Factors Affecting Teaching / शिक्षण को प्रभावित करने वाले कारक, Effective Teaching and the Teacher / प्रभावी शिक्षण एवं शिक्षक, Instructional Objectives and Lesson Planning / अनुदेशनात्मक उद्देश्य एवं पाठ नियोजन, Methods of Teaching / शिक्षण विधियाँ, Offline and Online Teaching Methods / ऑफ़लाइन एवं ऑनलाइन शिक्षण विधियाँ, Teaching Support System / शिक्षण सहायक प्रणाली, Evaluation Systems / मूल्यांकन प्रणाली, Sāṃkhya / सांख्य, Individual Behaviour / व्यक्तिगत व्यवहार, Human Resource Management / मानव संसाधन प्रबंधन, Domains of Child Development / बाल्यावस्था में विकास के क्षेत्र, Biological Basis of Emotion / संवेग का जैविक आधार, Upanishads and Bhagavad Gita / उपनिषद और भगवद्गीता, Central and Peripheral Nervous Systems / केन्द्रीय और परिधीय तंत्रिका तंत्र
  3. Paper - 1 | Unit - 2 | Research Aptitude: Research: Meaning, Features and Scientific Method / अनुसंधान: अर्थ, लक्षण व वैज्ञानिक विधि, Research Paradigms and Approaches / अनुसंधान के प्रतिमान एवं उपागम, Types of Research / अनुसंधान के प्रकार, Variables and Measurement / चर एवं मापन, Methods of Research / अनुसंधान की विधियाँ, Steps of Research / अनुसंधान के चरण, Sampling / प्रतिचयन, Tools and Methods of Data Collection / आँकड़ा संग्रह के उपकरण एवं विधियाँ, Data Analysis and Statistics in Research / आँकड़ा विश्लेषण एवं शोध सांख्यिकी, Thesis and Article Writing / शोध-प्रबंध एवं लेख लेखन, Application of ICT in Research / अनुसंधान में ICT का अनुप्रयोग, Research Ethics / शोध नैतिकता
  4. Paper - 1 | Unit - 3 | Comprehension: Literal Comprehension, Vocabulary and Language in Context, Inferential Comprehension, Critical Comprehension, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Restoration and Eighteenth-Century Drama, Modern British Fiction, William Shakespeare, Mid-Twentieth-Century and Contemporary British Fiction, American Drama
  5. Paper - 1 | Unit - 4 | Communication: Communication: Meaning, Nature and Process / संचार: अर्थ, प्रकृति एवं प्रक्रिया, Types and Levels of Communication / संचार के प्रकार एवं स्तर, Verbal and Non-verbal Communication / मौखिक एवं अमौखिक संचार, Semiotics and Meaning / संकेत विज्ञान एवं अर्थ, Models and Theories of Communication / संचार के मॉडल एवं सिद्धांत, Effective Communication / प्रभावी संचार, Barriers to Communication / संचार की बाधाएँ, Classroom Communication / कक्षा संचार, Mass Media: Types and Evolution / जनसंचार माध्यम: प्रकार एवं विकास, Mass Media and Society / जनसंचार एवं समाज, Digital and New Media / डिजिटल एवं नव माध्यम, Static General Knowledge / स्थैतिक सामान्य ज्ञान, Morphology and Syntax, Public Health Nutrition / जन स्वास्थ्य पोषण, Newtonian Motion and Stability, GK- Current Affairs / GK- समसामयिकी, Indian Economy / भारतीय अर्थव्यवस्था, Art and Architecture / कला और स्थापत्य, India after Independence / स्वतंत्रता के बाद भारत
  6. Paper - 1 | Unit - 5 | Mathematical Reasoning and Aptitude: Number System and Simplification / संख्या पद्धति एवं सरलीकरण, Algebra and Ages / बीजगणित एवं आयु, Percentage / प्रतिशतता, Ratio, Proportion, Partnership and Mixtures / अनुपात, समानुपात, साझेदारी एवं मिश्रण, Averages / औसत, Profit, Loss and Discount / लाभ, हानि एवं बट्टा, Simple and Compound Interest / साधारण एवं चक्रवृद्धि ब्याज, Time and Work / समय एवं कार्य, Speed, Time and Distance / चाल, समय एवं दूरी, Mensuration and Geometry / क्षेत्रमिति एवं ज्यामिति, Series / श्रेणी, Coding-Decoding / कूटलेखन-कूटवाचन, Relationships, Directions and Ranking / संबंध, दिशा एवं क्रम, Arrangements, Puzzles, Clock and Calendar / व्यवस्था, पहेलियाँ, घड़ी एवं कैलेंडर, Mathematical Foundations, Polity / राजव्यवस्था, जीवनी, Deconstruction, Gender and Queer Theory, Modern British and Irish Poetry, Central Force and Scattering, Chemical thermodynamics, Microscopic techniques, Philosophy of the Constitution / संविधान का दर्शन, Waves, Optics and Charged-Particle Motion, Membrane structure and function, Analysis
  7. Paper - 1 | Unit - 6 | Logical Reasoning: Structure of Arguments / युक्ति की संरचना, Terms, Definitions and Uses of Language / पद, परिभाषा एवं भाषा के उपयोग, Categorical Propositions / निरुपाधिक प्रतिज्ञप्तियाँ, Categorical Syllogism / निरुपाधिक न्यायवाक्य, Venn Diagrams / वेन आरेख, Deduction, Induction and Analogy / निगमन, आगमन एवं सादृश्यता, Fallacies / तर्कदोष, Indian Logic: Pramanas / भारतीय तर्कशास्त्र: प्रमाण, Anumana and Vyapti / अनुमान एवं व्याप्ति, Hetvabhasa / हेत्वाभास, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Aristotle / अरस्तू, Western Schools of Philosophy / पाश्चात्य दर्शन की विचारधाराएँ, Kant / कांट, Sadhana Paada, Vaiśeṣika / वैशेषिक
  8. Paper - 1 | Unit - 7 | Data Interpretation: Data and Graphical Representation / आँकड़े एवं आलेखीय निरूपण, Data Interpretation: Tables / आँकड़ा निर्वचन: तालिका
  9. Paper - 1 | Unit - 8 | Information and Communication Technology: Computer Fundamentals and Hardware, Memory, Storage and Data Representation, Computer Software, Office Applications, Multimedia and File Formats, Computer Networks, Internet and World Wide Web, Email and Online Communication, Cyber Security, Digital Ethics, IPR and Society, Cloud and Distributed Computing, Emerging Technologies, ICT in Education and Governance, Cyber Threats and Malware Attacks, Role of Internet and Web Services, Electronic Data Interchange and E-Commerce, Internet Fundamentals, Web Design & Development, Web Publishing & Hosting, Emerging Technologies, Terms & Abbreviations, Society, Law & Ethics, Keyboard Shortcuts, Website, Browser & Services, Protection of Geographical Indications / भौगोलिक संकेतों का संरक्षण
  10. Paper - 1 | Unit - 9 | People Development and Environment: Ecosystems and Biodiversity / पारितंत्र और जैव विविधता, Human and Environment Interaction / मानव और पर्यावरण की अंतःक्रिया, Development and Environment / विकास और पर्यावरण, Natural Resources – Forests, Water and Soil / प्राकृतिक संसाधन: वन, जल और मृदा, Energy Resources / ऊर्जा संसाधन, Air Pollution / वायु प्रदूषण, Water Pollution and Treatment / जल प्रदूषण और उपचार, Noise Pollution / ध्वनि प्रदूषण, Waste Management / अपशिष्ट प्रबंधन, Environmental Health and Toxicology / पर्यावरणीय स्वास्थ्य और विषविज्ञान, Climate Change and Global Environmental Issues / जलवायु परिवर्तन और वैश्विक पर्यावरणीय समस्याएँ, Natural Hazards and Disaster Management / प्राकृतिक प्रकोप और आपदा प्रबंधन, Indian Environmental Laws and Policies / भारतीय पर्यावरण कानून और नीतियाँ, International Environmental Agreements / अंतर्राष्ट्रीय पर्यावरण समझौते, Environment / पर्यावरण, Geography / भूगोल, Factory and Industry Systems / कारखाना और उद्योग व्यवस्थाएँ, Earth Materials, Surface Features and Processes, Communicable Diseases and Immunization / संक्रामक रोग और प्रतिरक्षण
  11. Paper - 1 | Unit - 10 | Higher Education System: Education in Ancient India / प्राचीन भारत में शिक्षा, Ancient Centres of Higher Learning / प्राचीन भारत के उच्च शिक्षा केंद्र, Colonial Education Policies and Commissions / औपनिवेशिक काल की शिक्षा नीतियाँ और आयोग, Colonial Colleges, Universities and Reformers / औपनिवेशिक कॉलेज, विश्वविद्यालय व सुधारक, Education Commissions and Policies after Independence / स्वतंत्र भारत में शिक्षा आयोग और नीतियाँ, National Education Policy 2020 / राष्ट्रीय शिक्षा नीति 2020, Types of Higher Education Institutions / उच्च शिक्षा संस्थानों के प्रकार, Learning Programmes and Academic Credits / अधिगम कार्यक्रम और अकादमिक क्रेडिट, Professional, Technical and Skill-Based Education / व्यावसायिक, तकनीकी और कौशल आधारित शिक्षा, Value Education and Environmental Education / मूल्य शिक्षा और पर्यावरण शिक्षा, Governance, Administration and Financing / शासन, प्रशासन और वित्तपोषण, Regulation, Accreditation and Ranking / उच्च शिक्षा का नियमन, प्रत्यायन और रैंकिंग
  12. Paper 2 | Unit 1 | Discrete Structures and Optimization: Propositional and Predicate Logic, Set Theory, Relations, Functions, Permutation, Combination and Probability / क्रमचय, संचय एवं प्रायिकता, Graph Theory, Group Theory, Digital Systems & Boolean Basics, Boolean Expression, Boolean Minimization, Optimization, Markov Chains
  13. Paper 2 | Unit 2 | Computer System Architecture: Logic Gates & Hardware, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep, Basics of COA, Register Transfer and Microoperations, Programming the Basic Computer, Instr Formats & Modes, Control Unit Design, Pipelining, Input Output Organisation, Cache Memory Organization, Multiprocessors
  14. Paper 2 | Unit 3 | Programming Languages and Computer Graphics: Language Design, C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, HTML Basics, XML, JavaScript-Basics, Java, Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing, OOPS with C++, Java Fundamentals, Array, String, IO & References, OOPS with Java
  15. Paper 2 | Unit 4 | 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, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  16. Paper 2 | Unit 5 | System Software and Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  17. Paper 2 | Unit 6 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  18. Paper 2 | Unit 7 | Data Structures and Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  19. Paper 2 | Unit 8 | Theory of Computation and Compilers: 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, 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
  20. Paper 2 | Unit 9 | Data Communication and 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, Cloud Computing, Mobile Computing
  21. Paper 2 | Unit 10 | Artificial Intelligence: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Fuzzy Sets, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms
  22. Live Classes: NTA UGC NET 2025 Live Class
  23. Paper 1 | Full Mock Tests:
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AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture introduces Linux memory allocation, beginning with the Buddy Allocator and progressing through SLOB, SLAB, and SLUB allocators before covering Huge Pages and NUMA. The Buddy Allocator manages physical memory in contiguous page blocks whose sizes are powers of two, splitting larger blocks on demand and merging adjacent same-size buddy blocks on free to reduce external fragmentation. A worked example traces an 8-page block splitting into 4-page and then 2-page blocks, followed by merging two adjacent 2-page buddy blocks into a 4-page block. The SLOB Allocator is presented as a simple, low-overhead allocator for small-memory systems that maintains a list of free blocks and uses first-fit search; its limitations include external fragmentation and slow linear searching, and it was removed from the Linux kernel in version 6.8. A four-row worked example demonstrates free-list operations: initial state, allocating 20 KB, allocating 15 KB, and freeing the first 20 KB block, with a memory bar from address 0 to 99. The SLAB Allocator maintains caches of pre-allocated objects organized as Cache → Slab (one or more pages) → Objects, where slabs contain multiple objects of the same size created in advance for fast reuse. The SLUB (Unqueued Slab) Allocator is then introduced as the default slab allocator in modern Linux, with a simpler data structure and better performance; its five-step working flow covers kernel request through object return, including what happens when an object is freed. The lecture concludes by introducing Huge Pages as larger-than-normal pages to reduce memory-management overhead and NUMA (Non-Uniform Memory Access) architecture, with a simple example contrasting local versus remote memory access speeds.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The slide titled 'Linux Memory Allocation' defines the Buddy Allocator as a Linux kernel mechanism for managing physical memory in blocks of contiguous pages. Bullets state it divides free memory into blocks whose sizes are 'powers of 2 pages,' splits a larger block when a smaller one is required, and merges adjacent same-size blocks with their buddy on free. It provides efficient allocation of 'physically contiguous pages' and helps reduce 'external fragmentation.' In red handwriting beneath the bullets, a powers-of-two sequence is written: '1, 2, 4, 8, 16' at first, then extended to '32, 64.'

  2. 2:00 – 5:00 02:00-05:00

    A worked example slide shows two stacked diagrams. The blue-headed 'BUDDY ALLOCATOR – SPLITTING' panel traces an 8 Pages block split into two 4 Pages blocks, then a 4 Pages block split into 2 Pages and 2 Pages alongside a remaining 4 Pages block. The green-headed 'BUDDY ALLOCATOR – MERGING' panel shows two adjacent yellow '2 Pages' blocks under a 'Buddy Blocks' bracket combining via a 'Merge' arrow into one green '4 Pages' block. Side 'Key Points' boxes list rules such as blocks of size 2^n pages (1, 2, 4, 8...) and that merging reduces fragmentation. The instructor underlines and circles key terms on the Buddy Allocator slide before transitioning to SLOB Allocator details, pointing out an 'Important Current-Linux Note' regarding SLOB removal.

  3. 5:00 – 10:00 05:00-10:00

    The SLOB Allocator slide describes it as a 'very simple, low-overhead kernel allocator intended for small-memory systems.' It maintained a 'simple list of free memory blocks' and used a 'first-fit style search to find a suitable free block.' A warning icon marks the note that SLOB is not present-day default and was removed from the Linux kernel in version 6.8, with SLUB becoming the default slab allocator. A 'Key Point' states SLOB focuses on simplicity and low memory overhead rather than maximum performance, with limitations including external fragmentation and slower linear searching. A four-row diagram then walks through memory operations: '1. Initial State,' '2. Allocate 20 KB,' '3. Allocate 15 KB,' and '4. Free First Block (20 KB),' each pairing a Free List table (Start Address, Size in KB) with a Memory bar marked 0 to 99, segments shifting between green 'Free' and red/yellow 'Allocated' blocks. Red handwritten checkmarks, underlines, and arrows link Free List entries to memory segments.

  4. 10:00 – 15:00 10:00-15:00

    The SLAB Allocator slide presents a definition line, five bullet points including 'Maintains caches of pre-allocated objects,' and a vertical diagram: Cache → Slab (Page or Multiple Pages) → a row of Object boxes. Side captions read 'Collection of slabs for a specific object type,' 'A slab contains multiple objects of the same size,' and 'Objects are created in advance and reused for fast allocation.' A red circle highlights 'Objects of the same type/size,' and a large red curly brace groups the three levels. Sections for 'Working of SLAB Allocator,' 'Advantages of SLAB,' and 'Limitations of SLAB' are indicated. Red underlines progressively appear across the definition, bullets, and diagram captions.

  5. 15:00 – 20:00 15:00-20:00

    The SLUB (Unqueued Slab) Allocator is introduced as the default slab allocator in modern Linux kernels, with a simpler data structure and better performance compared to SLAB. A visual flowchart illustrates the 5-step working flow of SLUB, from kernel request to return to kernel. The lecture discusses 'When an Object is Freed' and the 'Advantages of SLUB,' with red underlines highlighting key terms like 'simpler data structure' and 'performance and scalability.' The lesson then transitions to 'Huge Pages,' described as larger-than-normal memory pages to reduce overhead, and introduces 'NUMA (Non-Uniform Memory Access)' architecture and its impact on memory access time, with a 'Simple Example (NUMA)' diagram showing local versus remote memory access speeds.

  6. 20:00 – 20:59 20:00-20:59

    The final sampled frames continue the NUMA discussion, with the 'Simple Example (NUMA)' diagram visible showing local versus remote memory access speeds. The instructor appears to be concluding the lecture on Linux Memory Allocation, having covered Buddy Allocator, SLOB, SLAB, SLUB, Huge Pages, and NUMA. No new slides or major transitions are evident in this final window beyond the continuation of the NUMA example.

The lecture follows a clear pedagogical progression through Linux memory allocation mechanisms. It begins with the Buddy Allocator, establishing the foundational concept of power-of-two block sizes and the split/merge operations that manage physical contiguous pages while reducing external fragmentation. The worked example with 8-page, 4-page, and 2-page blocks makes the abstract split/merge rules concrete. The SLOB Allocator is then presented as a simpler alternative for constrained systems, with its first-fit search and list-based free block management contrasted against the Buddy Allocator's structured approach; its removal in kernel 6.8 signals a shift toward more sophisticated allocators. The four-row free-list example provides a practical demonstration of allocation and deallocation tracking. The SLAB Allocator introduces object-level caching with the Cache-Slab-Object hierarchy, addressing the need for fast allocation of frequently used kernel objects. SLUB refines this with a simpler data structure and better scalability, becoming the modern default. The lecture concludes by broadening scope to hardware-level memory management with Huge Pages and NUMA, connecting software allocation strategies to physical memory architecture. Key transitions include the move from page-level (Buddy) to object-level (SLAB/SLUB) allocation, and from software allocators to hardware memory topology.

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