Process Scheduling & Policies

Duration: 20 min

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Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Paper-1 & 2 | Basic Numeracy: अनुपात और समानुपात / Ratio and Proportion, Divisibility Rules, मिश्रण और एलिगेशन / Mixture and Alligation, Permutation and Combination, Logarithm, संख्या पद्धति / Number System, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, Sequence and Series (Series), समय, चाल और दूरी / Time, Speed and Distance, प्रतिशत / Percentage, औसत / Average, घन क्षेत्रमिति / Solid Mensuration, Age Problems, Arithmetic, Statistics, Probability, लाभ, हानि और बट्टा / Profit, Loss and Discount, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, Partnership, Speed Mathematics and Basic Mathematics, Algebra, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, समय और कार्य / Time and Work, Pipe and Cistern, RSSB Specific Videos - Basic Numeracy, 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. Paper-1 & 2 | Data Interpretation: आँकड़ा निर्वचन / Data Interpretation
  4. Paper-1 & 2 | General Mental Ability: Mental Ability, RSSB Specific Videos - Mental Ability
  5. Paper-1 & 2 | Logical Reasoning and Analytical Ability: श्रेणी / Series, कूट लेखन एवं कूट वाचन / Coding-Decoding, Data Sufficiency, अशाब्दिक तर्क / Non-Verbal Reasoning, Syllogisms, बैठक व्यवस्था एवं पहेलियाँ / Seating Arrangement and Puzzles, रक्त संबंध / Blood Relations, दिशा एवं दूरी / Direction and Distance, Analytical Reasoning (Counting Figures Reasoning), गणितीय संक्रियाएँ एवं लुप्त संख्या / Mathematical Operations and Missing Numbers, कैलेंडर एवं घड़ी / Calendar and Clock, Clock, घन, पासा एवं आकृतियों की गिनती / Cubes, Dice and Figure Counting, वेन आरेख, न्याय वाक्य एवं असमानता / Venn Diagrams, Syllogism and Inequalities, सादृश्यता एवं वर्गीकरण / Analogy and Classification, क्रम एवं रैंकिंग / Order and Ranking, कथन आधारित तार्किक विवेचन / Statement-Based Reasoning, Data Arrangement, वर्णमाला एवं संख्या परीक्षण / Alphabet and Number Test, Crypt Arithmetic
  6. Paper-1 & 2 | Decision Making and Problem Solving: आँकड़ों की पर्याप्तता एवं निर्णय क्षमता / Data Sufficiency and Decision Making
  7. Paper-1 | General Science: वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research, Biology, Chemistry, RSSB Specific Videos
  8. Paper-1 | General Awareness: राज्य विशेष सामान्य ज्ञान / State-Specific General Knowledge, समसामयिकी / Current Affairs
  9. Paper-2 | Fundamentals of Computer: Basics of COA, Number System, Floating Point Rep, Number Representation
  10. Paper - 2 | Digital Logic Systems: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits
  11. Paper-2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Linux OS, Distributed Systems
  12. 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, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  13. Paper-2 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. Paper-2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  15. Paper 2 | Oops, C++, Java: Language Design, OOPS with C++, Java, .Net Programming, Java Fundamentals
  16. 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
  17. Paper 2 | Emerging Trends and AI: Emerging Tech Trends, कंप्यूटर के मूल सिद्धांत / Computer Fundamentals, व्यापार, विपणन एवं उपभोक्ता संरक्षण / Trade, Marketing and Consumer Protection, कंप्यूटर नेटवर्क / Computer Networks
  18. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Advanced Algorithms
  19. Paper 2 | Data Communication and Network Security: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, 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, Ethical Hacking
  20. Paper-2 I Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  21. Paper-2 | Computer Organization and Architecture: Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations
  22. Paper-2 | Web Development: JavaScript-Basics, HTML Basics, CSS, XML
  23. Pedagogy: वृद्धि और विकास / Growth and Development, Concept of Pedagogy, संज्ञानात्मक प्रक्रियाएँ / Cognitive Processes, विकास के सिद्धांत / Theories of Development, समावेशी शिक्षा / Inclusive Education, Experiential Pedagogy, समाजीकरण और जेंडर / Socialisation and Gender, National Education Policy (NEP) 2020
  24. Live Sessions: RSSB Live Sessions
  25. RSSB Paper 1 - Full Mock Tests:
  26. RSSB Paper 2 - Full Mock Tests:
  27. SCI Previous Year Papers:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture introduces Linux process scheduling, beginning with preemptive scheduling and time sharing before comparing the three main policies: SCHED_NORMAL (CFS/EEVDF), SCHED_FIFO, and SCHED_RR. It concludes by transitioning to process creation using the fork() system call.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The lecture opens with a slide titled 'Preemptive Scheduling, Time Sharing & Priority.' The instructor explains that Linux uses preemptive scheduling, meaning a running process can be temporarily interrupted by the scheduler. A numbered diagram illustrates this: step 1 shows 'P1 Running,' followed by red text stating 'Time slice expires / higher priority process arrives.' Step 2 shows the 'Scheduler' is triggered to make a new decision, and step 3 shows 'P2 Running.' The instructor uses a red pen to circle key terms like 'P1 Running' and underline the trigger conditions, emphasizing that this mechanism improves system responsiveness and multitasking.

  2. 2:00 – 5:00 02:00-05:00

    The lesson transitions to a new slide titled 'Time Sharing.' The instructor explains that CPU time is divided among multiple processes, with each process getting a small time interval called a 'time slice.' A Gantt chart visualizes this by showing the CPU switching between Process 1 (P1), Process 2 (P2), and Process 3 (P3) over increasing time intervals from T1 to T5. The instructor underlines key phrases such as 'small time interval' and 'After its time slice, the scheduler may switch the CPU to another process.' A color-coded legend distinguishes between the different processes, and a 'Key Point' callout box summarizes how time sharing allows multiple tasks to appear to run simultaneously.

  3. 5:00 – 10:00 05:00-10:00

    The lecture moves to priority-based scheduling, defining how the scheduler considers the priority of processes while making decisions. The instructor highlights that in Linux, a lower 'nice value' is associated with higher scheduling priority for normal processes. The text on screen states: 'Higher scheduling priority -> Greater chance/preference for CPU time.' The instructor underlines important phrases like 'priority of processes' and 'nice value.' This section bridges the gap between basic time sharing and the specific Linux scheduling policies, establishing that priority is a core factor in CPU allocation.

  4. 10:00 – 15:00 10:00-15:00

    The instructor presents a comprehensive overview of Linux scheduling policies, comparing SCHED_NORMAL (CFS/EEVDF), SCHED_FIFO, and SCHED_RR. Step-by-step flow diagrams illustrate each policy. For SCHED_NORMAL, the diagram shows a 'Fair Scheduler (CFS / EEVDF)' that provides fair CPU sharing. For SCHED_FIFO, the flow shows 'Pick Highest Priority (First In, First Out)' and running until a higher priority process arrives. For SCHED_RR, the diagram shows processes 'Run for Time Quantum (tq)' and asks 'Time Quantum Expired?' to determine if the process is preempted. The instructor uses red annotations to highlight key differences in CPU time sharing and priority handling across the three columns.

  5. 15:00 – 19:42 15:00-19:42

    The lecture continues detailing the flows of SCHED_NORMAL, SCHED_FIFO, and SCHED_RR, emphasizing that FIFO uses strict priority-based scheduling without preemption within the same priority, while RR operates on a round-robin basis. The final section transitions to a new topic: 'Process Creation using fork().' A slide explains that fork() is a system call used to create a new process in Linux. A summary table breaks down the return values of fork(), stating that '> 0: Returned to Parent -> value is Child's PID.' This marks the end of the scheduling policies discussion and the beginning of process creation concepts.

The lecture systematically builds understanding of Linux scheduling from fundamental concepts to specific policies. It starts by defining preemptive scheduling and time sharing, using diagrams and Gantt charts to visualize how the CPU is shared among processes. It then introduces priority as a decision factor, specifically mentioning the Linux 'nice value.' The core of the lecture compares the three main scheduling policies (SCHED_NORMAL, SCHED_FIFO, SCHED_RR) using flowcharts to show their distinct logic for CPU allocation. Finally, it transitions to process creation via fork(), linking scheduling decisions back to how processes are initially created. The progression moves from 'what' (preemption/time sharing) to 'how' (policies/flows) to 'where it starts' (fork).

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