Performance of Demand Paging

Duration: 4 min

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Module outline

  1. Quantitative Aptitude: Number System, Divisibility Rules, HCF LCM, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Mixture and Alligation, Partnership, Age Problems, Time and Work, Pipe and Cistern, Speed Time and Distance, Algebra, Arithmetic, Data Interpretation, Sequence and Series (Series), Logarithm, Powers and Exponents (Surds and Indices), Permutation and Combination, Probability, Speed Mathematics and Basic Mathematics, Trigonometry
  2. Logical Reasoning: Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Syllogisms, Inequality, Data Sufficiency, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Venn Diagram, Logical Sequence Of Words, Calendar, Clock, Cubes & Dices, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Noun, Pronoun, Adjectives, Verb, Adverb, Tenses, Subject Verb Agreement (Verb Noun Agreement), Articles, Preposition, Conjunction, Modals, Determiner, Vocabulary, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Active Passive Voice (Voice), Direct and Indirect Speech, Sentence Construction
  4. Data Structures (Domain Test): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  5. Algorithms (Domain Test): Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms
  6. OOPs (Domain Test): Object Oriented Programming (OOPS)
  7. DBMS (Domain Test): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, 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
  8. SQL (Domain Test): SQL
  9. Operating Systems (Domain Test): Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  10. Computer Networks (Domain Test): 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, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
  11. Coding: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir
  12. Written English Test: English Writing Ability
  13. Psychometric Test: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
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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