Solution of Control Hazards

Duration: 7 min

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Module outline

  1. About Course: About the Course
  2. CS | 01 | Digital Logic and Circuits and Discrete Mathematical Structures: Digital Systems & Boolean Basics, Number System, Number Representation, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Permutation and Combination
  3. CS | 02 | Computer Organization and Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Multiprocessors
  4. CS | 03 | Data Structures and Algorithm: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Complexity Theory, Advanced Algorithms
  5. CS | 04 | Problem Solving through C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  6. CS | 05 | Object Oriented Techniques: Object Oriented Technology, Java
  7. CS | 06 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Unix OS
  8. CS | 07 | Database Management Systems: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization, Query Processing & Optimization, File Organization & Indexing
  9. CS | 08 | 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
  10. CS | 09 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  11. CS | 10 | Internet Technology, Web Design and Web Technology: Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, JavaScript-Basics, HTML Basics
  12. CS | 11 | System Analysis And Design: Fundamentals of Systems and Information Systems, SDLC and Development Approaches, Software Documentation and Software Requirements Specification (SRS), SDD and Quality Assurance, Security, Risk Management & Maintenance
  13. CS | 12 | Information Security and Cyber Laws: 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
  14. CS | 13 | Computer Graphics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing
  15. GS Paper | 01 | Indian and World Geography: Geography
  16. GS Paper | 02 | History: History
  17. GS Paper | 03 | Indian Economy & Social Development: Indian Economy
  18. GS Paper | 04 | General Science: Biology, Chemistry, वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research
  19. GS Paper | 05 | Elementary Maths: संख्या पद्धति / Number System, Divisibility Rules, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, प्रतिशत / Percentage, लाभ, हानि और बट्टा / Profit, Loss and Discount, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, अनुपात और समानुपात / Ratio and Proportion, औसत / Average, समय और कार्य / Time and Work, समय, चाल और दूरी / Time, Speed and Distance, Algebra, घन क्षेत्रमिति / Solid Mensuration, आँकड़ा निर्वचन / Data Interpretation, Arithmetic, Statistics, Probability, Sequence and Series (Series), मिश्रण और एलिगेशन / Mixture and Alligation, Calculus, Trigonometry, Vectors, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, यूक्लिडीय ज्यामिति और क्षेत्रमिति / Euclidean Geometry and Mensuration, सांख्यिकी और प्रायिकता / Statistics and Probability, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers, समतल क्षेत्रमिति / Plane Mensuration, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics
  20. GS Paper | 06 | Indian Polity and Governance: Polity
  21. GS Paper | 07 | Current Events: समसामयिकी / Current Affairs
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AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video details solutions for control hazards in computer architecture pipelines. The instructor covers flushing/stalling as the worst-case scenario, followed by compiler techniques like NOPs and code rearrangement. The lecture concludes with hardware prediction methods, specifically comparing single-bit and 2-bit prediction strategies using state diagrams. Visual aids include a structured slide listing methods and a handwritten diagram illustrating the logic behind 2-bit prediction and policy changes.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a slide titled "Solution of control hazards," introducing "Flushing/Stalling." The instructor emphasizes this is the "worst-case scenario," underlining "remove the computed data" and "don't work at all." He explains that when a branch is mispredicted, the pipeline must discard instructions fetched on the wrong path. He draws a sequence of instructions labeled I1 through I6 to visualize this. He illustrates a scenario where instructions I3, I4, I5, and I6 are fetched but discarded if the branch condition is not met. He writes "I110 - I140" and "I16" to represent instruction addresses, demonstrating how the processor handles execution flow when a hazard occurs. The visual focus remains on the slide text and the instructor's annotations, highlighting the performance penalty of this approach.

  2. 2:00 – 5:00 02:00-05:00

    The lecture shifts to compiler-assisted techniques. The slide lists "NOP (no-operation)," defined as a placeholder where the compiler "don't execute any instruction here," creating a pipeline bubble. Next, the instructor discusses "Code rearrangement or delayed load," explaining that "smart compilers" can reorder instructions to execute those "independent from the current logic" first. He draws a simple state diagram with two states, B=0 and B=1, representing branch outcomes. He illustrates transitions based on conditions C=0 and C=1, showing how a simple prediction mechanism works. He circles the states and draws arrows to indicate the flow, setting the stage for more complex prediction logic. The visual content includes the slide text and the instructor's hand-drawn diagrams, simplifying the abstract concept of compiler optimization.

  3. 5:00 – 7:10 05:00-07:10

    The final segment features a handwritten slide titled "Estimate Method/ Predictive Method with 2-bit." This diagram illustrates a 4-state machine for branch prediction. The instructor explains "2 Stage Prediction," noting a "2 mistakes then policy change" rule, meaning the prediction only flips after two consecutive errors. He contrasts this with "Single Stage Prediction with 1 bit," where a "1 mistake policy change" occurs, making it more volatile. The diagram shows four states in a loop, with transitions labeled C=0 and C=1. He circles specific states and transitions in red ink to highlight the execution path and conditions for policy changes. The text "2 mistakes then policy change" and "1 mistake policy change" is clearly visible, emphasizing the robustness of the 2-bit counter.

The video systematically builds an understanding of control hazard mitigation, moving from hardware penalties to software optimizations and finally to hardware prediction algorithms. The progression from the destructive nature of flushing to the constructive nature of code rearrangement highlights trade-offs in pipeline design. The detailed comparison of 1-bit and 2-bit prediction methods provides a concrete example of how state machines improve accuracy. The combination of slide text and handwritten diagrams effectively reinforces theoretical concepts with practical visualizations.

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