Why Pipelines Break? Structural & Data Hazards Explained

Pipelining improves CPU performance, but it also introduces pipeline hazards that can break the smooth execution of instructions. In this video, we explore pipeline hazards in detail and understand how modern processors handle them. First, we explain Structural Hazards and why they occur when hardware resources are limited. Then we move to Data Hazards, which happen when instructions depend on the results of previous instructions. We also discuss the three main solutions used in processors: Stalling (Pipeline bubbles) Forwarding / Bypassing Instruction Scheduling To make things clearer, we solve real examples step by step and then update the CPU datapath by adding a Forwarding Unit and pipeline registers for control signals, ensuring each instruction carries its own control information (RegWrite, ALUOp, etc.) through the pipeline stages. Topics covered: Pipeline hazards overview Structural hazards Data hazards Stalling technique Forwarding / bypassing unit Instruction scheduling Updated pipelined datapath Control signals moving through pipeline registers This video is part of the Computer Architecture / RISC-V series, where we break down complex CPU design concepts step by step.