计算机系信息处理实验室 lecture 12 i/o system xlanchen@05/13/2005

计算机系•信息处理实验室

Lecture 12 I/O System

xlanchen@05/13/2005

xlanchen@05/13/2005 Understanding the Inside of Windows 2000 2计算机系

信息处理实验室

Contents

I/O System Components

I/O Data Structures

Driver Loading, Initialization, and Installation

I/O Processing



I/O System Components

I/O manager



The flow of a typical I/O request



I/O Manager

The I/O manager defines the orderly framework, or model, within which I/O requests are delivered to device drivers.

Packet driven

I/O request packet (IRP)

Flexible I/O services



Device Drivers

Types

File system drivers

Windows 2000 drivers

Legacy drivers

display drivers

WDM drivers

Bus drivers

Function drivers

Filter drivers



user-mode drivers Virtual device drivers (VDDs) Win32 subsystem printer drivers

Driver componentsClass driversPort drivers Miniport drivers



Layering of a FSD and a disk driver



Adding a layered driver



Structure of a Drive

The I/O system drives the execution of device drivers

Primary device driver routines



Plug and Play (PnP) Manager



Power Manager

Requirement

hardware must comply with ACPI specification

The six system power states

See table 9-2



System power-state transitions

Sleeping

waking



I/O Data Structures

File Objects Driver Objects and Device Objects I/O Request Packets I/O Completion Ports



File Objects

File Object Attributes

Filename

Current byte offset

Share modes

Open mode flags

Pointer to device object

Pointer to the volume parameter block (VPB)

Pointer to section object pointers

Pointer to private cache map



Opening a file object



Driver Objects and Device Objects

A driver object represents an individual driver in the system.

A device object represents a physical or logical device on the system and describes its characteristics



The driver object



I/O Request Packets

IRP is where the I/O system stores information it needs to process an I/O request.



Data structures involved in a single-layered driver I/O request



IRP Stack Locations

IRP

a fixed header

one or more stack locations

IRP Buffer Management

Buffered I/O

Direct I/O

Neither I/O



I/O Completion Ports

The IoCompletion ObjectApplications use the IoCompletion executive object, which is exported to Win32 as a completion port, as the focal point for the completion of I/O associated with multiple file handles.



I/O completion port operation



Driver Loading, Initialization, and Installation

Explicit loading

Enumeration-based loading



The Start Value

boot-start (0)

system-start (1)

auto-start (2)

demand-start (3)



Device Enumeration

PnP manager

primary bus driver

device tree



Example device tree



Devnodes



Driver Installation



I/O Processing

Types of I/OSynchronous I/O and Asynchronous I/O

Fast I/OMapped File I/O and File CachingScatter/Gather I/O



Control flow for an I/O operation



I/O Request to a Single-Layered Driver



Servicing an Interrupt

Phrase 1



Phrase 2



Completing an I/O Request

Phrase 1



Phrase 2



I/O Requests to Layered Drivers



Completing a layered I/O request



Queuing associated IRPs



Completing associated IRPs



I/O Completion Port Operation



Synchronization

计算机系 信息处理实验室 lecture 12 i/o system xlanchen@05/13/2005

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计算机系信息处理实验室 lecture 12 i/o system xlanchen@05/13/2005