I/O Device Management

The CPU is fast. The real world is slow. This module explores how the Operating System bridges this gap, managing communication with Disks, Network Cards, and Keyboards without stalling the system.

Module Roadmap

  1. I/O Hardware Interface
    • Understanding Controllers and Buses (PCIe, SATA).
    • Port-Mapped I/O vs Memory-Mapped I/O (MMIO).
    • The Memory Gap: How devices map to physical addresses.
  2. Interrupts and DMA
    • Why polling kills performance.
    • The Interrupt lifecycle (IVT, ISR, Context Switch).
    • Direct Memory Access (DMA): Zero-CPU copy.
  3. Disk Scheduling
    • Anatomy of Latency: Seek Time vs Rotational Delay.
    • Elevator Algorithms: SCAN, C-SCAN, SSTF.
    • Modern Storage: NVMe Queues and io_uring.
  4. Buffering and Caching
    • Smoothing the flow: Double Buffering and Ring Buffers.
    • The Page Cache: Write-Back vs Write-Through.
    • Zero Copy I/O (mmap, sendfile).
  5. RAID Levels
    • Redundant Array of Independent Disks.
    • Striping (RAID 0), Mirroring (RAID 1), and Parity (RAID 5).
    • Calculated recovery using XOR.
  6. Module Review

    • Flashcards, Cheat Sheet, and Interview Questions.

I/O Device Management

[!NOTE] This module explores the core principles of I/O Device Management, deriving solutions from first principles and hardware constraints to build world-class, production-ready expertise.

1. Learning Objectives

  • Visualize how a CPU command travels over the bus to a device controller.
  • Implement conceptual drivers using MMIO and DMA patterns.
  • Calculate RAID parity and Disk Seek distances.
  • Compare legacy I/O (Polling/PIO) with modern high-performance I/O (Interrupts/DMA/Zero Copy).

Module Chapters