Tsinghua University class network operating system _
Network lesson link: http://www.xuetangx.com/courses/course-v1:TsinghuaX+30240243X_tv+2015_T1/about
Courses wiki page: http://os.cs.tsinghua.edu.cn/oscourse/OS2015/
Q & A exchanges and curriculum area: https://piazza.com/tsinghua.edu.cn/spring2015/30240243x/home
Curriculum Experiment & Practice: https://github.com/chyyuu/mooc_os
Operating System Definition
1. The operating system is a program control
- A system software
- Control program execution process, prevent errors and improper use of computer
- User program execution, the user program provides a variety of services
- User-friendly computer system
2. The operating system is a resource manager
- An intermediate layer between the application and the hardware
- Manage various computer hardware and software resources
- Computer hardware and software tools to provide efficient access to resources
- Resolve resource conflicts and ensure equitable use of resources
Status of the operating system
ucore teaching operating system
Operating system kernel features
1. Concurrent
- Program running multiple computer systems exist, the need for operating system management and scheduling
2. Share
- When running multiple programs at the macro level to reflect the "simultaneous" visit
- Multiple programs at runtime shared resources to achieve mutually exclusive micro
3. Virtual
- Using multi-channel programming technology that allows each user think there is a computer for him to provide services
4. Asynchronous
- Execution of the program is not consistent in the end, but stop and go, forward speed unpredictable
- As long as the same operating environment, os need to ensure that the results should be the same as running
The evolution of the operating system
1. Single treatment system
2. Batch System
System for batch processing job is done, but the memory is always run only one job
Problems: during the job if the IO request occurs, the CPU will have to wait for high-speed low-speed IO operations is completed, resulting in reduced CPU resource utilization and system throughput.
3. multiprogramming system
Multiprogramming systems allow multiple programs into the memory and run. When an IO request to suspend the program due to run, CPU operation immediately turn to another channel program. He let the various components of the system as much as possible, "busy", it takes very little time to switch tasks, to the parallel work between the components of the system, so that resources are fully utilized, system throughput.
Problems: no ability to provide human-computer interaction
4. The time-sharing system
The runtime processor sharing system is divided into a short time slice, the allocated time slice in turn to each processor online job. Because the computer is fast, give each user their own exclusive feel as if a computer.
Time-sharing system is a system to achieve human-computer interaction.