Linux Kernel design and implementation (i) Introduction to the kernel __linux

Turn from: http://www.cnblogs.com/wang_yb/archive/2012/08/15/2640972.html

This article briefly introduces the basic concepts of kernel-related.

Main content: Single kernel and microkernel kernel version number

1. Single Kernel and microkernel

	Principle	Advantage	Disadvantage
Single Core	The entire kernel is running on a large kernel address space.	1. Simple. 2. High efficiency: All kernels are in a large address space, so calls and invocation functions are similar to each other in the kernel, with little performance overhead.	A crash of a feature can cause the entire kernel to be unusable.
Micro-core	The kernel is divided into separate processes by function. Each process runs independently on its own address space.	1. Security: The various services of the kernel run independently, and a service hangs without affecting other services.	Calls between the kernel's services involve interprocess communication, which is more complex and less efficient.

Although Linux kernel is based on a single kernel, but after so many years of development, but also has some of the characteristics of the microkernel. (embodies the principle of Linux practical Supremacy)

The main features are: Support dynamic loading kernel module support symmetric multi-processing (SMP) kernel can preempt (preemptive), allow kernel to run tasks with priority ability to execute without distinguishing thread and process 2. Kernel version number

The kernel version number consists primarily of four arrays. For example, version number: 2.6.26.1,

2-Major Version number

6-from version number or sub version number

26-Revision Number

1-Stable version number

The minor version number indicates whether this version is stable (even) or development (odd), and the version number in the example above is the stable version.

Stable versions are available for enterprise-class environments.

upgrades to revision numbers include bug fixes, new drivers, and additions to new features.

The stable version number is primarily a modification of some critical bugs.