Centos 7 升级内核 5.x

一、升级内核
1.更新 Centos 7 软件包

yum -y update

2.安装下面的包，让更新速度更快

yum -y install yum-plugin-fastestmirror

3.检查操作系统版本

[[email protected] ~]$ cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
[[email protected] ~]$ cat /etc/os-release
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"
 
CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"

4.检查内核版本

[[email protected] ~]$ uname -a
Linux node03 3.10.0-957.5.1.el7.x86_64 #1 SMP Fri Feb 1 14:54:57 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

5.添加ELRepo仓库

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm

6.查看可以使用的kernel

yum --disablerepo="*" --enablerepo="elrepo-kernel" list available

7.安装内核 5.x

yum --enablerepo=elrepo-kernel install kernel-ml -y

二、优化内核启动参数
1.修改 /etc/default/grub，在 GRUB_CMDLINE_LINUX 最后加上 xen_blkfront.max_indirect_segments=256
2.修改内核启动顺序

grub2-set-default 0

3.更新内核启动配置

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

4.优化内核参数到开机启动

echo "echo never > /sys/kernel/mm/transparent_hugepage/enabled" >> /etc/rc.local
echo "echo never > /sys/kernel/mm/transparent_hugepage/defrag" >> /etc/rc.local