LRTF

Duration: 4 min

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  1. About Course: UPPSC Course Overview
  2. Interview Preparation & Guidance: Interview Preparation
  3. Paper 1 | General 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, वर्णमाला, समास, संधि, 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)
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  7. Paper 1 | Cyber Security: Society, Law & Ethics, Cyber Threats and Malware Attacks, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Electronic Data Interchange and E-Commerce, Physical Security and Cryptography Basics, Intrusion Detection Systems (IDS), Cyber Safety and Security, Ethical Hacking
  8. Paper 1 | Computer Organization and Architecture: Basics of COA, Programming the Basic Computer, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design
  9. Paper 1 | 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
  10. Paper 1 | Design and Analysis of Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
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  12. Paper 1 | Discrete Structures and Theory of Logic: Permutation and Combination, Set Theory, Relations, Functions, Propositional and Predicate Logic, Graph Theory, Group Theory
  13. Paper 1 | Software Project Management: Software Project Management
  14. Paper 2 | Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS, Linux OS, Security
  15. Paper 2 | Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment, Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Pushdown Automata & CFG, Complexity Theory
  16. Paper 2 | Artificial Intelligence & High Performance Computing: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Natural Language Processing, Emerging Tech Trends
  17. Paper 2 | Image Processing: Digital Image Fundamentals, Image Enhancement, Image Restoration, Color Image Processing, Image Compression
  18. Paper 2 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  19. Paper 2 | Computer Graphics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing
  20. Paper 2 | Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, Java
  21. Paper 2 | Soft Computing: Fuzzy Sets, Artificial Neural Networks, Genetic Algorithms
  22. Paper 2 | Distributed System: Distributed Systems
  23. UPPSC Live Class Recordings: UPPSC Polytechnic Lecturer 2025 (CS)
  24. Previous Year Papers:
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AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture covers CPU scheduling algorithms, specifically Longest Job First (LJF) and its pre-emptive variant, Longest Remaining Time First (LRTF). The instructor defines LJF, noting on-screen text that "Process having longest Burst Time will get scheduled first." He demonstrates a non-preemptive example using a table of five processes (P1-P5) with varying arrival and burst times. He constructs a Gantt chart, showing how P1 runs first, followed by P4, P5, P3, and finally P2, based on the longest available burst time. The second half introduces LRTF, emphasizing its pre-emptive nature where the process with the longest *remaining* time is chosen, even if it was already running.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the Longest Job First algorithm, highlighting on-screen text that states "Process having longest Burst Time will get scheduled first." He presents a table with five processes (P1-P5) and their Arrival/Burst Times. He then draws a timeline (Gantt chart) to solve a non-preemptive example. He starts with P1 at time 0, runs it for 3 units (finishing at t=3). At t=3, he compares available processes P2 (BT=2), P3 (BT=4), and P4 (BT=5), selecting P4 because it has the longest burst time. He continues this logic, selecting P5 (BT=6) which runs from t=8 to t=14, then P3 (BT=4) from t=14 to t=18, and finally P2 (BT=2) from t=18 to t=20.

  2. 2:00 – 3:42 02:00-03:42

    The topic shifts to Longest Remaining Time First (LRTF), described as pre-emptive. A table shows three processes (P1-P3) arriving at time 0 with burst times 2, 4, and 8. The instructor draws a Gantt chart showing P3 running initially. He updates the remaining burst times in the table (crossing out original values and writing new ones, e.g., P3's BT changes from 8 to 4). He demonstrates preemption by switching between P3 and P2 as their remaining times fluctuate. At time 8, when remaining times for P1, P2, and P3 are all equal (2 units), he switches to P1, then P2, then P3, finishing the schedule at time 11. This illustrates how LRTF handles ties and preemption dynamically.

The lecture distinguishes between non-preemptive and pre-emptive scheduling based on job length. LJF minimizes average waiting time but can cause starvation for short jobs. LRTF adds pre-emption, allowing shorter jobs to run if their remaining time becomes the longest relative to others, though the example shows frequent context switching. Both algorithms prioritize longer tasks, contrasting with Shortest Job First. The visual Gantt charts and table updates provide clear evidence of the scheduling logic.

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