Working Set Strategy

Duration: 6 min

This video lesson is available to enrolled students.

Return to /learn/COGNIZANT-PREPARATION/operating-systems/virtual-memory/thrashing-allocation/asset-working-set-strategy after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. Communication Round: Vocabulary, Subject Verb Agreement (Verb Noun Agreement), Tenses, 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), Direct and Indirect Speech, Active Passive Voice (Voice), Verbal Analogy (Word Based Analogy), Articles, Preposition, Conjunction, Sentence Construction, English Writing Ability, Communication Assessment
  2. Quantitative Aptitude: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Speed Time and Distance, Percentage, Average, Powers and Exponents (Surds and Indices), Time and Work, Mensuration and Geometry, Age Problems, Pipe and Cistern, Probability, Profit and Loss, Simple Interest and Compound Interest, Algebra
  3. Analytical and Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Directions (Direction Test), Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Logical Sequence Of Words, Puzzle Solving (Puzzles), Syllogisms, Seating Arrangements, Calendar, Clock, Blood Relations, Cubes & Dices, Venn Diagram, Analytical Reasoning (Counting Figures Reasoning)
  4. Cognizant Gaming Aptitude: Gamified / Game Based Aptitude
  5. Java (Cluster 1): Java
  6. ANSI SQL MySQL (Cluster 1,2,3): SQL
  7. HTML, CSS, JavaScript (Cluster 1,3): HTML, CSS, JavaScript
  8. Python (Cluster 2): Python for Placements by Yash Sir
  9. Cloud Fundamentals (Cluster 2): Emerging Tech Trends
  10. C# (Cluster 3): C#
  11. OOPs: Object Oriented Programming (OOPS)
  12. Technical Assessment (Coding): Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Pseudo Codes
  13. Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. DBMS: 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
  15. Operating Systems: 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
  16. 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, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture introduces the Working Set Strategy in operating systems, focusing on the locality model of process execution. The instructor explains that a program moves through different localities, where a locality is defined as a set of pages actively used together. Using a page reference table, he demonstrates how to calculate the working set at specific time points ($t_1$ and $t_2$) by analyzing the pages referenced within a fixed window size ($\Delta$). The lesson highlights the dynamic nature of memory requirements as a process transitions between different localities.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video begins with a slide titled 'The Working Set Strategy'. The instructor reads the first bullet point: 'This approach defines the locality model of process execution.' He then explains the second point, stating that as a process executes, it moves from locality to locality. He defines a locality as 'a set of pages that are actively used together.' He points to the third bullet point, noting that a program is generally composed of several different localities which may overlap. He gestures towards the 'page reference table' at the bottom of the slide, which lists a sequence of numbers like 2, 6, 1, 5, 7, 7, 7, 7, 5, 1, 6, 2, 3, 4, 1, 2, 3, 4, 4, 4, 3, 4, 3, 4, 4, 4, 1, 3, 2, 3, 4, 4, 4, 3, 4, 4, 4.

  2. 2:00 – 5:00 02:00-05:00

    The instructor focuses on the diagram below the table, which shows time points $t_1$ and $t_2$ with a window size $\Delta$. He explains that the working set at time $t$, denoted as $WS(t)$, consists of the pages referenced in the interval $[t - \Delta, t]$. He draws a box around the sequence ending at $t_1$, which includes the numbers 2, 6, 1, 5, 7, 7, 7, 7, 5, 1. He identifies the unique pages in this window as {1, 2, 5, 6, 7}. He writes $WS(t_1) = \{1, 2, 5, 6, 7\}$ and counts the number of unique pages, writing a '5' below it to represent the working set size. He then moves to $t_2$, drawing a box around the sequence ending there, which includes 3, 4, 4, 4, 3, 4, 3, 4, 4, 4, 1. He identifies the unique pages as {3, 4}. He writes $WS(t_2) = \{3, 4\}$ and counts the unique pages, writing a '2' below it.

  3. 5:00 – 5:40 05:00-05:40

    The instructor concludes the example by comparing the two working sets. He points to the numbers 3 and 4 in the reference table, emphasizing that these are the pages currently being used at time $t_2$. He explains that the working set size has decreased from 5 to 2, indicating a shift in the process's locality. He reiterates that the working set strategy helps in determining the number of frames a process needs in memory to avoid thrashing. He gestures back and forth between the two time points to show the transition from one locality to another.

The lesson progresses from theoretical definition to practical application. It starts with the definition of locality and the working set strategy, then moves to a concrete example using a page reference string. The instructor demonstrates how to calculate the working set size at different time points by analyzing the recent history of page accesses within a fixed window $\Delta$. This illustrates the dynamic nature of memory requirements for a process.

Loading lesson…