Disadvantage of TLB

Duration: 8 min

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  1. About the course: About the Course
  2. Mathematical Aptitude: संख्या पद्धति / Number System, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, Divisibility Rules, प्रतिशत / Percentage, अनुपात और समानुपात / Ratio and Proportion, औसत / Average, लाभ, हानि और बट्टा / Profit, Loss and Discount, समय और कार्य / Time and Work, घन क्षेत्रमिति / Solid Mensuration, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, समय, चाल और दूरी / Time, Speed and Distance, Age Problems, मिश्रण और एलिगेशन / Mixture and Alligation, Algebra, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, Pipe and Cistern, Trigonometry, Statistics, आँकड़ा निर्वचन / Data Interpretation, Arithmetic, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers
  3. Logical Reasoning: श्रेणी / Series, कूट लेखन एवं कूट वाचन / Coding-Decoding, सादृश्यता एवं वर्गीकरण / Analogy and Classification, रक्त संबंध / Blood Relations, दिशा एवं दूरी / Direction and Distance, क्रम एवं रैंकिंग / Order and Ranking, अशाब्दिक तर्क / Non-Verbal Reasoning, बैठक व्यवस्था एवं पहेलियाँ / Seating Arrangement and Puzzles, Syllogisms, वेन आरेख, न्याय वाक्य एवं असमानता / Venn Diagrams, Syllogism and Inequalities, गणितीय संक्रियाएँ एवं लुप्त संख्या / Mathematical Operations and Missing Numbers, वर्णमाला एवं संख्या परीक्षण / Alphabet and Number Test, कथन आधारित तार्किक विवेचन / Statement-Based Reasoning, Analytical Reasoning (Counting Figures Reasoning), घन, पासा एवं आकृतियों की गिनती / Cubes, Dice and Figure Counting, कैलेंडर एवं घड़ी / Calendar and Clock, Clock
  4. General Knowledge: वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research, Chemistry, Biology, History, Geography, Polity, Indian Economy, समसामयिकी / Current Affairs, Static General Knowledge, राज्य विशेष सामान्य ज्ञान / State-Specific General Knowledge
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  6. Environmental Science: Environment
  7. Unit 1 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  8. Unit 2 | COA: Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations, Programming the Basic Computer
  9. Unit 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  10. Unit 3 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  11. Unit 4 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  12. Unit 5 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management
  13. Unit 6 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Transaction Management, Concurrency Control
  14. Unit 7 | 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
  15. Unit 8 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  16. Unit 9 | Object Oriented Programming: OOPS with C++
  17. Unit 10 | Web Development: HTML Basics, CSS, JavaScript-Basics, XML, Node.js, Git & Github
  18. Unit 11 | 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
  19. Unit 12 | IoT: Emerging Tech Trends, Cloud Computing, कंप्यूटर नेटवर्क / Computer Networks
  20. Unit 13 | Artificial Intelligence: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms
  21. Unit 14 | E-Commerce: Electronic Data Interchange and E-Commerce, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Physical Security and Cryptography Basics, Cyber Safety and Security
  22. Unit 15 | Multimedia: Multimedia
  23. Unit 16 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis, DSA using Python
  24. Full Length Mock Tests — General Paper:
  25. Full Length Mock Tests — Computer Science (Paper II):
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The lecture addresses the disadvantages of the Translation Lookaside Buffer (TLB) in computer architecture, specifically focusing on the overhead associated with context switching. The instructor explains that because a TLB caches page table entries for a single process, switching to a new process often necessitates flushing the entire TLB, which is a significant performance penalty. To mitigate this, he presents solutions such as using multiple TLBs, which is expensive, or 'wiring down' critical entries. These wired-down entries, typically for kernel code, remain in the TLB across context switches to ensure efficient access to system-level data structures. The lecture uses a slide with text and a diagram to illustrate the flow from logical address to physical address and the role of the TLB in this process.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by highlighting the primary disadvantage of TLBs. The slide text explicitly states: 'TLB can hold the data of one process at a time and in case of multiple context switches TLB will be required to flush frequently.' He writes '2 MM' and '3 MM' on the slide, likely referring to the number of memory accesses or costs associated with a TLB miss versus a hit. He draws a diagram with 'P1', 'P2', 'P3' to illustrate multiple processes competing for the limited TLB space, emphasizing the need to flush the buffer when switching between these processes. The diagram on the right shows the CPU sending a logical address to the TLB, which contains page number and frame number mappings. If there is a TLB hit, the physical address is formed; if there is a miss, the page table is accessed.

  2. 2:00 – 5:00 02:00-05:00

    The instructor transitions to solutions. The slide text reads: 'Use multiple TLB's but it will be costly.' He explains that while using multiple TLBs is an option, it increases hardware cost. He then introduces the concept of 'wired down' entries, circling the text on the slide. He writes 'wired down' and explains that these entries cannot be removed. He draws arrows and writes 'P1', 'P2', 'P3' again, indicating different processes. He writes '64' and '64' (likely page table size or TLB size) to illustrate the scale of the problem. He draws a circle around the TLB entries to show which ones are protected. The slide text further clarifies: 'Some TLBs allow certain entries to be wired down, meaning that they cannot be removed from the TLB. Typically, TLB entries for kernel code are wired down.'

  3. 5:00 – 8:00 05:00-08:00

    The instructor elaborates on the 'wired down' concept. He writes 'TLB miss' and points to the page table, explaining the fallback mechanism. He draws a circle around the TLB entries again, emphasizing that some entries are permanent. He writes '64' and '64' again, likely referring to the number of entries. He emphasizes that kernel code entries are wired down, meaning they stay in the TLB even during context switches. This ensures that the kernel's page table entries are always available, reducing the overhead of reloading them every time the OS switches processes. The instructor gestures towards the diagram, showing how the physical address is formed from the frame number and offset, and how the TLB miss path leads to the page table.

The lecture effectively connects the theoretical disadvantage of TLB flushing with practical hardware solutions. By explaining the 'wired down' mechanism, the instructor clarifies how operating systems optimize memory management by preserving critical kernel entries in the TLB, balancing performance and cost. The visual aids, including the slide text and the instructor's annotations, reinforce the concept that not all TLB entries are treated equally, with kernel entries receiving special protection to maintain system efficiency.

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