Udacity: Introduction to Operating Systems

[Weiting-Zhang]

操作系统

优达学城 CS8803 操作系统课程的学习笔记。

P1L1 课程概览

课程涵盖内容

• processes and process management
• threads and concurrency
• resource management: scheduling, memory management
• OS services for communication and I/O
• OS support for distributed services
• Systems software for data center and cloud environments

推荐课本

• Operating System Concepts
• Modern operating Systems
• Operating Systems Three Easy Pieces

P1L2 操作系统简介

课程预览

• What is an operating system?
• What are key components of an operating system?
• Design and implementation considerations of operating systems

操作系统是什么

• 概念类比
  An operating system is like a toy shop manager.（以下只标注了操作系统的作用，略去了 shop manager 类比的内容）
  • Direct operating resources
    • control use of CPU, memory, peripheral devices
  • Enforce working policies
    • fair resource accessed limits to resource usage...
  • Mitigate difficulty of complex tasks
    • abstract hardware details(System calls)
• 一张图来说明下：
  
• A special piece of software that abstracts and arbitrates the underlying hardware system( abstract means to simplify what the hardware actually looks like, and arbitrate means to manage, to oversee, to control the hardware use.)

操作系统举例

• Desktop Operating Systems 桌面操作系统
  • microsoft windows(early 1980s)
  • unix-based(originated at Bell Labs, late 1960s)
    • Mac OSX(BSD)
    • Linux
• Embedded Operating Systems 嵌入式操作系统
  • Android(Linux 的嵌入式版本)
  • iOS
  • Symbian

操作系统要素

• Abstractions 抽象
  • process, thread, file, socket, memory page
• Mechanisms 机理
  • create, schedule, open, write, allocate
• Policies 策略
  • least recently used(LRU), earliest deadline first(EDF)