Performance of Demand Paging

Duration: 4 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 1 | General Studies: State Wise GK
  3. Paper 1 | Information and Communication Technology: Role of Internet and Web Services, Security in Mobile and Wireless Computing
  4. Paper 1 | Current Affairs: GK- Current Affairs
  5. Paper 2 | Discrete Mathematical Structure: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Probability
  6. Paper 2 | Digital Computer Organization And Architecture: Number System, Number Representation, Sequential Circuits, Combinational Circuit, Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer
  7. Paper 2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  8. Paper 2 | Programming Languages & Object-Oriented Programming Concepts: Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  9. 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
  10. Paper 2 | Data Structure And Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Advanced Algorithms
  11. Paper 2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS
  12. Paper 2 | 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, Complexity Theory
  13. 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
  14. 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, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization, Enhanced Data Models
  15. Paper 2 | Computer Network And Information Security: Introduction to CN, Data Communication, Application Layer, Hardware basics, Cyber Threats and Malware Attacks, Network Security, 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
  16. 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
  17. Paper 2 | Current Trends & Technologies: Emerging Tech Trends, Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Fuzzy Sets, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms, Artificial Intelligence, Data Warehousing & Mining, Electronic Data Interchange and E-Commerce, Terms & Abbreviations
  18. Paper 2 | Full Length Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The lecture focuses on calculating the effective access time in demand paging systems, a critical performance metric in operating systems. The instructor introduces the fundamental formula: Effective Access Time = (1 - p) * ma + p * page fault service time. He meticulously defines 'p' as the page fault rate or probability of a page fault occurring, and 'ma' as the standard memory access time. Through a detailed numerical example, he demonstrates how a relatively low page fault rate can drastically increase the effective access time compared to the base memory access time, highlighting the performance penalty associated with page faults.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the formula for "Effective Access time for Demand Paging" displayed on the slide: (1 - p) x ma + p x page fault service time. He defines 'p' as the page fault rate or probability of a page fault and 'ma' as memory access time. He begins a numerical example on the whiteboard, assigning values: ma = 10, page fault service time = 1000, p = 0.01, and (1-p) = 0.99. He calculates the first term as 0.99 * 10 = 9.9 and the second term as 0.01 * 1000 = 10. Finally, he sums these values to get an effective access time of 19.9, circling the result on the board. He underlines the terms in the formula to show correspondence with the numbers. He writes "lo" under ma and "1000" under page fault service time.

  2. 2:00 – 3:45 02:00-03:45

    The instructor analyzes the result of the calculation, pointing to the formula components on the slide. He highlights that despite a low page fault rate of 1%, the effective access time nearly doubles from 10 to 19.9 due to the high cost of page fault service time (1000). He emphasizes the importance of minimizing page faults to maintain system performance. He gestures towards the written calculation to reinforce the mathematical derivation. The lecture concludes this segment by solidifying the relationship between page fault rates and overall memory performance. He explains that the "1000" represents the time taken to bring a page from disk, which is much slower than memory access. He points to the "19.9" result to show the final effective time.

The lesson effectively bridges theoretical formulas with practical numerical application. By calculating the effective access time, students learn that even rare page faults can significantly degrade performance because the service time is much higher than standard memory access. This underscores the critical need for efficient page replacement algorithms in operating systems to keep the page fault rate low.

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