Operating System learning Notes _12_I/O Management--I/O Management Overview

I/OManagement--i/oManagement Overview

First, I/O control mode

1.i/o Equipment Concept

  I/o device : controller , operator ( Central processor ) and memory all devices

I/O Operation : is the transfer data operation between the memory and the media of the peripheral.

2.i/o Equipment Classification

(1) category by Interactive object : Human-Computer interaction equipment, etc.

(2) Sort by Interactive direction : input and so on.

(3) classification by peripheral characteristics : Transmission devices , or character transfer devices.

3.i/o Management Objectives

  i/o

The goal of equipment management is : to raise the efficiency ; Easy to use ; easy to control.

4.i/o Application Interface

provides the user interface used by the device : Command Interface and programming interface .

Equipment allocation and release : before using the device, you need to assign the device and the corresponding channel , controller .

Device Access and control : includes concurrent access and error handling .

I/o Buffering and scheduling : The goal is to improve I/O The efficiency of the interview .

5.i/o Interface Control mode

One of the main tasks of device management is to control the data transfer between the device and the memory or processor , the I/O between peripherals and memory There are four kinds of control methods , For example, the following is described.

(1) control method of program interview

(2) Interrupt Control Method

(3) dma[ Direct Memory addressing ] Way

"DMA and interrupt control frees up the CPU from a lot of useless work"

(4) Channel mode

"von Neumann computer system: arithmetic, controller, memory, I/O Device "

Second, I/O Software Hierarchy

1.i/o The goal of the software

(1) device independence.

(2) Unified naming.

2.i/o Software Hierarchy

  I/o software , i/o interface.

The general I/o software structure is divided into four layers.

User Layer

device independent layer ( operating system

Device drivers

Interrupt handlers

Interrupt Handler : I/O device interrupt mode is control input and memory and CPU The primary way to transfer data between device drivers : I/O device drivers are software modules that deal directly with hardware.

    " interrupt handlers and device drivers are typically completed by the hardware developer "

    device independent layer : i/o software except for device drivers

User-level software : The user uses the device's system call or API. The usual I/O is called by the library system.

Copyright notice: This article Bo Master original article. Blog, not reproduced without consent.

Operating System learning Notes _12_I/O Management--I/O Management Overview