Centos7 upgrade kernel

Before updating, check the current Centos system kernel version:

# uname -r

3.10.0- 327.10.1. el7.x86_64

First go to Tsinghua's TUNA or USTC's elrepo to download the kernel rpm package suitable for you. Mine is 64-bit, and the address is as follows:

https://mirrors.tuna.tsinghua.edu.cn/elrepo/kernel/el7/x86_64/RPMS/

As you can see,

kernel-lt :Linux LTS long-term maintenance version of the kernel, currently 4.4.78
kernel-ml :Linux MainLine mainline version kernel, usually the latest kernel, the current version is 4.12.3

Use wget to download the required rpm package, and then use rpm -ivh xxxx.rpm to install; or you can use it directly

rpm -Uvh URL address of rpm package to install

E.g:

rpm  -Uvh https://mirrors.tuna.tsinghua.edu.cn/elrepo/kernel/el7/x86_64/RPMS/kernel-ml-4.12.3-1.el7.elrepo.x86_64.rpm

(Kernel-*-devel is the header file required by the system, generally used more, it is recommended to install ^_^)

View the default startup sequence

# awk -F\' '$1=="menuentry "{print $2}' /etc/grub2.cfg 

CentOS Linux(4.4.4-1.el7.elrepo.x86_64)7(Core)

CentOS Linux(3.10.0-327.10.1.el7.x86_64)7(Core) 

CentOS Linux(0-rescue-c52097a1078c403da03b8eddeac5080b)7(Core)

The default boot sequence is to start from 0, and the new kernel is inserted from the beginning (currently at 0, while 4.4.4 is at 1), so you need to select 0

# grub2-set-default0

Then reboot to use the new kernel, the following is the kernel version used after the restart:

# uname -r 

4.4.4- 1. el7.elrepo.x86_64

This step can be done or not, delete the old kernel.

# yum remove kernel kernel-headers

So far, you're done. Next time, let's talk about the BBR congestion control algorithm enabled by the Linux kernel above 4.9.