Operating system "generation" division (P235)
* The operating system has three generations
1. Unordered module structure:
Direct mutual call between modules, no hierarchy, forming a mesh call mode.
2. Hierarchy:
Divide system procedures into several basic modules according to functions.
Then, according to its role and interrelationship, it is divided into different levels.
3. Micronuclear structure:
The kernel running under the core state uses hierarchies and constitutes a basic operating system.
The process layer of the client / server mode is running under the user state.
Customer: User process.
Server: The process of providing services in the operating system.
9.2 Overview of Micro Nuclear (P237)
* Take the core of the operating system into two levels of microennuclear and servers.
The micro-kernel provides a public foundation of various operating systems.
The subsystem of various operating systems is provided by the server and the user interface.
9.2.1 Microennuclear Concept
* Microconcord:
The small core of the operating system,
It refines the core functions needed by various operating systems.
Form the basic functions of the microennote.
User file server memory server network server | | | core-based microennuclear | hardware
Micro-kernel operating system model
9.2.2 Processes & Threads (P239)
In the micronary system:
1. Process: Only the unit allocated, no longer a unit of dispatching.
2. Thread: The minimum unit of operation is performed in the process.
3. Thread composition
Thread structure: thread identifier, scheduling status information,
Core stack pointer, user stack pointer and private storage area.
5. Relationship between processes and threads (P240)
A process can have multiple threads;
Resource allocation to the process, all threads of the same process share all resources for the process;
The processor is assigned to the process, and the thread is run on the process.
Threads need collaboration synchronization during the execution process.
