I/O Management and Disk Scheduling

Chapter 11

CS 431 -- Operating Systems

Dr. Tim McGuire

Sam Houston State University

Categories of I/O Devices

Categories of I/O Devices

Categories of I/O Devices

Differences in I/O Devices

Differences in I/O Devices

Techniques for Performing I/O

Techniques for Performing I/O

Evolution of the I/O Function

Evolution of the I/O Function

Evolution of the I/O Function

Direct Memory Access

Typical DMA Block Diagram

Direct Memory Access

DMA and Interrupt Breakpoints

Single-bus, Detached DMA

Single-bus, Integrated DMA-I/O

I/O Bus

Operating System Design Objectives

Operating System Design Objectives

A Model of I/O Organization

I/O Buffering

I/O Buffering

No Buffering

Single Buffer

Single Buffer

Single Buffer

Double Buffer

Circular Buffer

Disk Performance Parameters

Disk Performance Parameters

Disk Scheduling Policies

Disk Scheduling Policies

Disk Scheduling Policies

Disk Scheduling Policies

Disk Scheduling Policies

Disk Scheduling Policies

Disk Scheduling Policies

Disk Scheduling Policies

RAID 0 (non-redundant)

RAID 1 (mirrored)

RAID 2 (redundancy through Hamming code)

RAID 3 (bit-interleaved parity)

RAID 4 (block-level parity)

RAID 5 (block-level distributed parity)

Data Mapping for RAID Level 0 Array

Disk Cache

Least Recently Used

Least Recently Used

Least Frequently Used

Frequency-based Replacement

UNIX I/O Structure

Windows NT 4.0 I/O Manager

Disk Data Layout

Disk Layout Using Constant Angular Velocity