yum 源可以配到国内的镜像来加速 阿里云，网易，搜狐都可以
这里给个阿里云的说明 http://mirrors.aliyun.com/hel...
先升级 CentOS 到 6.8 Final
yum update
先导入公钥
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
导入源
rpm -Uvh http://www.elrepo.org/elrepo-release-6-6.el6.elrepo.noarch.rpm
然后可以选择安装最新版内核，或者稳定版内核
最新版
yum –enablerepo=elrepo-kernel install -y kernel-ml
稳定版
yum --enablerepo=elrepo-kernel install kernel-lt -y
最后编辑 /etc/grub.conf 启动文件
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You do not have a /boot partition. This means that
# all kernel and initrd paths are relative to /,eg.
# root (hd0,0)
# kernel /boot/vmlinuz-version ro root=/dev/sda1
# initrd /boot/initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/boot/grub/splash.xpm.gz
hiddenmenu
title CentOS (3.10.104-1.el6.elrepo.x86_64)
root (hd0,0)
kernel /boot/vmlinuz-3.10.104-1.el6.elrepo.x86_64 ro root=UUID=e70a0f35-5468-435d-b625-5924aee0a8ad rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet
initrd /boot/initramfs-3.10.104-1.el6.elrepo.x86_64.img
title CentOS (2.6.32-642.11.1.el6.x86_64)
root (hd0,0)
kernel /boot/vmlinuz-2.6.32-642.11.1.el6.x86_64 ro root=UUID=e70a0f35-5468-435d-b625-5924aee0a8ad rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet
initrd /boot/initramfs-2.6.32-642.11.1.el6.x86_64.img
title CentOS (2.6.32-358.el6.x86_64)
root (hd0,0)
kernel /boot/vmlinuz-2.6.32-358.el6.x86_64 ro root=UUID=e70a0f35-5468-435d-b625-5924aee0a8ad rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet
initrd /boot/initramfs-2.6.32-358.el6.x86_64.img
title顺序从上往下 0，1，2
默认新装的应该排在最上面
所以把default值改成0
然后重启
查看版本信息
#cat /etc/redhat-release CentOS release 6.8 (Final) # uname -r 3.10.104-1.el6.elrepo.x86_64
搞定
