Working Set Strategy

Duration: 6 min

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Module outline

  1. Quantitative Ability: Speed Mathematics and Basic Mathematics, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Speed Time and Distance, Number System, HCF LCM, Data Interpretation, Age Problems, Mixture and Alligation, Partnership, Algebra, Sequence and Series (Series), Mensuration and Geometry, Arithmetic
  2. Reasoning Ability: Puzzle Solving (Puzzles), Seating Arrangements, Coding Decoding, Blood Relations, Directions (Direction Test), Syllogisms, Data Sufficiency, Ranking, Order and Sequence, Series (Number and Letter Series) (Numerical Relations and Reasoning), Logical Sequence Of Words, Calendar, Clock, Cubes & Dices, Analytical Reasoning (Counting Figures Reasoning), Data Arrangement, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning)
  3. Verbal Ability: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Vocabulary, Sentence Completion (Fill in the blanks), Active Passive Voice (Voice), Direct and Indirect Speech, Subject Verb Agreement (Verb Noun Agreement), Tenses, Preposition, Articles, Sentence Correction (Error Correction)
  4. Programming Basics (MCQs + Interview): C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir
  5. OOPs (MCQs + Interview): Object Oriented Programming (OOPS)
  6. DBMS (MCQs + Interview): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Transaction Management, Decomposition Properties & 4NF, Concurrency Control, Database Recovery, File Organization & Indexing, Relational Algebra, Database Security & Authorization
  7. SQL (MCQs + Interview): SQL
  8. Operating Systems (MCQs + Interview): Introduction to OS, Process Management, CPU Scheduling, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Process Synchronization, Disc Scheduling, File Management, Security
  9. Computer Networks (MCQs + Interview): 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
  10. Coding: Coding Questions by Yash Sir
  11. HR Interview: MR & HR Interview Preparation
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.

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