Ubuntu Kernel configuration overview

Today I saw the default Kernel configuration of Ubuntu12.04 linux-souce-3.2.19, which is perfect, stable, and balanced in performance between Debian and rhel. For companies that are not very demanding, it is still very good, let's take a look at a few important part of the configuration: 1, Ubuntu uses a very high version of The linux-3.2.19 transformation, this is more than Debian 6, rhel6 is much higher, and later version 2.6.32 is used. This is also a feature of Ubuntu. Radical

Today I saw the Ubuntu 12.04 linux-souce-3.2.19 default Kernel configuration, very perfect, stable, Performance balance between Debian and rhel. For enterprises that do not have high requirements, it is still very good. Let's take a look at several important configurations:

1, Ubuntu uses a very high version of The linux-3.2.19 transformation, This is much higher than Debian6, rhel6 are a lot higher, the latter is used to 2.6.32 version, this is also the characteristics of Ubuntu. This is not the same as that of the radical. We need to pass our own tests and adopt them properly. Never compile such a new kernel on our Debian and rehl easily, which may be ugly, compatibility issues with various supported libraries.

2. general settings

Like Debian, Ubuntu has enabled the slub memory allocation mechanism (slab) version, which is more suitable for large-scale cpus numa deployment. in rhel and CentOS, it is also supported by the traditional slab. However, they do not all use the optimize for size option. In fact, the kernel will be smaller and the performance will be better, but it is best to test it, I support enabling (my own kernel is only 1.6 Mb). They have enabled the kernel debugging module, which greatly affects the performance, we recommend that you disable debugging analysis options such as kprobes oprofile unless you are an analyst.

3. Module options:

Both Ubuntu and rhel centos enable the module security check function in which checksum effectively prevents rookit backdoors.

4. io scheduling:

Like Ubuntu and rhel and centos, CFQ is used as the default scheduler. In fact, if you are a vps provider and pure web server, enabling this is good, but if you are using a high-pressure database, we suggest you change it to elevator scheduling deadline. (Oralce-linux is the deadline used)

5. processor options:

Ubunt and rhel. similar to Debian, the general x86cpu is enabled, but the CPU type is not selected. We need to change this. In addition, the preemption is enabled, and in order to support desktops, like rhel and centos, supports Resource Allocation of kvm virtual machines in the mild preemption mode. If you do not use a kvm host, you are advised to change it to the traditional serverless preemption mode without using a desktop. The most important thing is that timer frequency is set to 250 like Debian. I think this is a very good value, and rhel is set to 1000, which wastes a lot of cpu resources for switching, my opinion is that unless your cpu clock speed is greater than 1000 GB, the network card bandwidth reaches 1 GB, and there are a large number of ddos attacks, the centos rhel 250 is honestly changed.