Problem with Pipelining

Duration: 5 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 2 | Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep
  3. Paper 2 | Computer Organization And Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Control Unit Design, Instr Formats & Modes, Programming the Basic Computer
  4. Paper 2 | Analog And Digital Communication: Introduction to Communication Systems & Random Signals, Analog Communication Systems, Information Theory & Digital Communication Fundamentals, Digital Modulation & Detection Techniques, Error Control, Synchronization & Multiple Access Techniques
  5. Paper 2 | Programming in C: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  6. Paper 2 | Data Structures And Programming: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  7. Paper 2 | Algorithms: Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  8. 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
  9. Paper 2 | Operating System: 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
  10. Paper 2 | Databases: 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
  11. Paper 2 | Information Systems and Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Paper 2 | 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
  13. Paper 2 | Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, CSS, XML, HTML5
  14. Paper 2 | Cyber Security And Emerging Technologies: Emerging Tech Trends
  15. Paper 2 | Cloud Technology: Cloud Computing
  16. Paper 2 | Probability and statistics: Probability, Statistics
  17. Paper-1 English: Vocabulary, Preposition, Articles, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Cloze Test (Cloze Passage), Sentence Construction
  18. Paper 1 General Mental Ability & Logical reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Powers and Exponents (Surds and Indices), Algebra, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Mental Ability, Age Problems, Partnership, Arithmetic, Speed Mathematics and Basic Mathematics, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Venn Diagram, Analogy
  19. Paper-1 General Knowledge & Current Affairs: State Wise GK, History, Geography, GK- Current Affairs, Static General Knowledge
  20. Full Length Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The lecture introduces a pipelining problem asking students to consider five instructions with specified clock requirements for the Fetch (F), Decode (D), Execute (E), and Write Back (WB) stages. The instructor presents a table listing the number of clock cycles each instruction requires for each stage, followed by an empty timing grid numbered 1 through 18. The core method involves mapping each instruction's stage durations onto the timeline, using red strikethroughs on the table to track consumed cycles and filling the grid row by row. Stalls are marked with X where an instruction must wait for a resource or dependency. The completed timeline shows I1 as F D D E WB, I2 as F X D D E E WB, I3 as F F X D X E E E E WB WB, I4 as X F X D D D X E E WB, and I5 as F X X X D D X E WB WB. The lecture then transitions to a conceptual slide explaining that different pipeline stages may have different delays depending on the instruction type, and that if each instruction takes one clock, a pipelined processor achieves CPI (Clock Per Instruction) = 1 in the long run. The final segment returns to the problem slide, reinforcing the connection between the theoretical CPI concept and the practical stall analysis.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The slide displays the heading "Q Consider 5 instruction with following clock requirement?" above a table with columns F, D, E, WB and rows I1 to I5 filled with small integers. Below is an empty timing grid with columns 1 through 18 and rows I1 to I5. A column number in the grid header is highlighted in orange, moving from 14 to 2 to 8, marking the clock cycle being discussed. The instructor begins filling the I1 row, crossing out F and D entries in red on the table while writing "F" in column 1 and "D" in column 2 on the timeline. By the end of this window, the I1 row is completed as "F D D E WB" across columns 1 through 5, with all corresponding table entries crossed out.

  2. 2:00 – 5:00 02:00-05:00

    The instructor continues filling the timeline grid in red handwriting, adding I2 as "F X D D E E WB" with X marks indicating stall cycles. I3 is added as "F F X D X E E E E WB WB" and I4 as "X F X D D D X E E WB". The I5 row is filled progressively, completing as "F X X X D D X E WB WB". Red diagonal strikethroughs are drawn over table cells as each instruction's cycles are consumed. A separate text slide appears stating that pipeline stages may have different delays and that "If each instruction takes one clock then with pipe-line processor in long run, we achieve CPI(Clock Per Instruction) = 1". Red underlines are drawn beneath key phrases including "one clock" and "pipe-line processor in long run" to emphasize the CPI concept.

  3. 5:00 – 5:21 05:00-05:21

    The final segment returns to the problem slide titled "Q Consider 5 instruction with following clock requirement?" showing the table with columns F, D, E, WB and rows I1 to I5, with several numeric entries crossed out in red. The completed timeline grid is visible below, displaying all five instruction rows with their stage sequences and X marks for stalls. This closing view reinforces the connection between the theoretical CPI explanation and the practical stall analysis performed throughout the lecture.

The lecture teaches how to analyze pipeline stalls by mapping instruction stage durations onto a timing grid. The key method is to track each instruction's F, D, E, and WB cycle requirements from the table, place them sequentially on the timeline, and insert X marks where stalls occur due to resource conflicts or dependencies. The central concept is that pipeline stages can have different delays depending on instruction type, and the ideal case where each instruction takes one clock yields CPI = 1 in the long run. The worked example with five instructions demonstrates how variable stage durations and stalls affect the overall pipeline performance, providing a concrete foundation for understanding CPI calculations in pipelined processors.

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