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OS (Operating System)
OS design
- ① traditional operating system architecture
- Unstructured OS (first generation): function-oriented structure messy and difficult to maintain.
- The modular structure OS (second generation): modules interact with each other through an interface. Module - Interface Method . Disadvantages: chaotic, there is no dividing line module.
- Hierarchical structure OS (Third Generation): In order to solve disorderly module to hierarchical management. Bottom-laying module . Disadvantages: complexity leads to inefficiency.
- ② client / server model C / S mode
- The client has a stand-alone processing power.
- The client may send a request to the server when needed.
- The client process its echo message.
- Cons: Server paralysis leading to the platform is not available, the client all the failures.
- ③ object-oriented programming techniques (SR)
- Object : have attributes and methods.
- Object classes : Many objects have the same approach in practice, but to create the same look inefficient method for each object. Therefore, using the object class defines a set of generally similar type .
- Inheritance : A new class based on an existing class definition, as its sub-categories . Some public variables defined in the parent class, subclass inherits a method to make and add their own features. Parent can have multiple children classes, subclasses can have more than one parent class multiple inheritance .
- ④ microkernel OS structure (Modern Structure)
- Small enough kernel : provide only minimal basis for building OS.
- Based on C / S structure : Implementing IO process.
- Separation of wit and strategy
- Object-oriented technology
- ⑤ microkernel basic functions
- Process (thread) management
- Low-level memory management
- Interrupt handling and caught
- Disadvantages: Due to the server (device not mean 'server') are more context switches more frequently, less efficient, if the number of the server into the micro-kernel, but also reduces the capacity becomes large.