SRTF Scheduling

Duration: 7 min

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Inside: a video lesson and guided study material.

Module outline

  1. About the Course: About the Course
  2. Section 1 | Language (Hindi): भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
  3. Section 1 | Language (उर्दू भाषा — 22 प्रश्न (निश्चित)): Spelling & Diacritics, Grammar (اسم, فعل, صفت, ضمیر), Vocabulary, Idioms & Proverbs, Comprehension
  4. Section 1 | Language (বাংলা / बांग्ला भाषा — 22 प्रश्न (निश्चित)): Bangla Script and Sounds, Bangla Grammar and Usage, Bangla Word Formation and Vocabulary, Reading and Text Interpretation
  5. Section 1 | Language (English): Vocabulary, Noun, Subject Verb Agreement (Verb Noun Agreement), Adjectives, Tenses, Pronoun, Verb, Adverb, Preposition, Articles, Determiner, Conjunction, Modals, Active Passive Voice (Voice), Direct and Indirect Speech, Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Construction, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Verbal Analogy (Word Based Analogy), Facts, Inference and Judgements
  6. Section 2 | Primary Maths & Reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Mensuration and Geometry, Age Problems, Arithmetic, Powers and Exponents (Surds and Indices), Algebra, Probability, Trigonometry, Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence
  7. Section 2 | General Awareness (GK + Current Affairs): Polity, Physics, Biology, State Wise GK, Chemistry, History, Geography, Indian Economy, Environment, GK- Current Affairs, Static General Knowledge
  8. Section 3 | Computer System and Org. (CSO): Basics of COA, Floating Point Rep, Cache Memory Organization, Instr Formats & Modes, Programming the Basic Computer, Input Output Organisation, Register Transfer and Microoperations, Control Unit Design
  9. Section 3 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, SQL, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control
  10. Section 3 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Process Synchronization
  11. Section 3 | Computer Networks: 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, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics
  12. Section 3 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Shortest Path Algos
  13. Section 3 | Theory Of Computation & Compiler Design: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization
  14. Section 3 | Emerging Trends (AI, Societal Ethics & MS Office): Artificial Intelligence, Emerging Tech Trends, Society, Law & Ethics, MS Office Applications
  15. Section 3 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Maintenance and Configuration Management, Software Testing
  16. Section 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  17. Section 3 | OOPS, C++, JAVA, HTML: OOPS with C++, Java, HTML Basics, CSS
  18. Section 3 | Java: Java Fundamentals, Array, String, IO & References
  19. Section 3 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  20. Section 3 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  21. Section 3 | Multimedia: Multimedia
  22. BPSC Previous Year Papers:
  23. BPSC Full Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a comprehensive analysis of the Shortest Remaining Time First (SRTF) scheduling algorithm, emphasizing its pre-emptive nature and optimality in minimizing average waiting time. The instructor begins by defining SRTF as a dynamic scheduling method where the CPU is allocated to the process with the smallest remaining burst time. A critical feature highlighted is that whenever a new process enters the ready state, a scheduling decision is immediately triggered. If this new process has a smaller CPU burst requirement than the remaining time of the currently running process, pre-emption occurs. The video establishes that this specific version of SRTF is considered optimal because it guarantees the minimal average waiting time among all scheduling algorithms. The instruction then transitions to practical application, utilizing a structured table format with columns for Arrival Time (AT), Burst Time (BT), Completion Time (CT), Turn Around Time, and Waiting Time. The instructor demonstrates the algorithm by populating these tables with numerical data for processes P0 through P4, showing specific values such as an Arrival Time of 1 and Burst Time of 7 for the first process. Visual aids include a hand-drawn timeline at the bottom of the screen, which marks intervals and process identifiers like P0 to visualize execution order. The instructor modifies burst times for processes, changing values from 7 to 6 and 5 to 4, to illustrate how changes in input affect the scheduling outcome. A Gantt chart is constructed below the table, correlating visual bars with calculated time metrics. The segment concludes with a correction note regarding a calculation typo, reinforcing the importance of accuracy in deriving Turn Around Time as Completion Time minus Arrival Time.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video introduces the Shortest Remaining Time First (SRTF) algorithm, explicitly defining it as a pre-emptive scheduling strategy. On-screen text states 'Shortest Remaining Time First (SRTF) (Pre-emptive)' and explains the core logic: 'whenever a process enters in ready state, again we make a scheduling decision.' The instructor details that if the new process has a 'smaller CPU burst requirement than the remaining CPU burst of the running process,' the current process is pre-empted. The segment concludes with a definitive statement on the algorithm's efficiency, noting 'This version (SRTF) is also called optimal is it guarantee minimal average waiting time.' This theoretical foundation sets the stage for subsequent numerical examples.

  2. 2:00 – 5:00 02:00-05:00

    The instruction shifts to a practical demonstration using a scheduling table with columns for Arrival Time, Burst Time, Completion Time, Turn Around Time, and Waiting Time. The screen displays process rows P0 through P4 populated with numerical data, such as 'Arrival Time 1 and Burst Time 7 for the first process.' A hand is seen drawing a timeline at the bottom, marking intervals and process identifiers like P0. One frame shows a completed table with handwritten calculations, including 'Turn Around Time derived as 8 minus 1 equals 7.' The instructor modifies burst times for P0 (changing 7 to 6) and P1 (changing 5 to 4), demonstrating the dynamic nature of SRTF. A man appears on screen explaining steps while pointing at row P2, and the timeline progresses with numbers 0, 1, 2, 3, and 4 indicating time units.

  3. 5:00 – 6:44 05:00-06:44

    The final segment consolidates the SRTF analysis by displaying a table with process details (P.No, Arrival Time, Burst Time) and constructing a Gantt chart below it. The instructor points at the chart to explain the progression of execution blocks P0, P1, and P2. The screen displays text labels including 'Arrival Time', 'Burst Time', 'Completion Time', 'Turn Around Time', and 'Waiting Time' alongside the header 'SRTF Scheduling'. A correction note is displayed regarding a calculation typo, emphasizing precision in the derivation of metrics. The visual correlation between table values and Gantt chart bars is maintained throughout, ensuring students understand how the abstract calculations translate into a visual timeline of process execution.

The video systematically progresses from theoretical definition to practical application, ensuring students grasp both the logic and implementation of SRTF. The core concept is pre-emption based on remaining burst time, which distinguishes it from non-pre-emptive Shortest Job First. The optimality claim is supported by the algorithm's ability to minimize average waiting time, a critical metric in operating systems. The use of tables and Gantt charts provides a dual representation: quantitative data for calculation practice and visual timelines for conceptual understanding. The instructor's modifications to burst times illustrate the algorithm's responsiveness, while the correction note highlights common pitfalls in manual calculation. This structured approach allows learners to verify their own computations against the visual evidence provided.

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