CentOS7开启Google TCP-BBR优化算法

概述

之前抱着试试看的心态入手了Virmach 最便宜的KVM构架的VPS

没想到速度如此之慢…… 跟国内的链接速度实在感人……

到手折腾了一下，今天重装成CentOS7的系统

最近很火的Google TCP-BBR优化算法可以在KVM构架的VPS里面开启，今天就试试了。

这是2016年9月份才开源的一个优化网络拥堵的算法。

开源地址

https://github.com/google/bbr

注意这不是Google官方的产品。

使用必读

不支持OpenVZ虚拟！

安装前需要备份重要数据，安装完可能会导致系统无法启动！

系统无法修改请尝试修改引导！或者重装系统！

安装方式

1. 安装elrepo提供的kernel4.9

增加elrepo源

cat > /etc/yum.repos.d/elrepo.repo << EOF
[elrepo-kernel]
name=ELRepo.org Community Enterprise Linux Kernel Repository - el7
baseurl=http://elrepo.org/linux/kernel/el7/\$basearch/http://mirrors.coreix.net/elrepo/kernel/el7/\$basearch/http://jur-linux.org/download/elrepo/kernel/el7/\$basearch/http://repos.lax-noc.com/elrepo/kernel/el7/\$basearch/http://mirror.ventraip.net.au/elrepo/kernel/el7/\$basearch/
enabled=1
gpgcheck=0
EOF

可能存在yum更新内核时候找不到升级包，请检查/etc/yum.conf是否过滤了kernel
找到改文件将exclude=kernel* centos-release*注销，再尝试安装
安装elrepo替换4.9内核及grub2

yum -y install kernel-ml grub2

查看4.9内核是否安装成功

 ls -l /boot/vmlinuz*

回显结果类似：

-rwxr-xr-x. 1 root root 5393008 Mar  4 16:31 /boot/vmlinuz-0-rescue-56751acc5351469882eb49d16e0d7f16
-rwxr-xr-x. 1 root root 5393328 Dec 25 12:00 /boot/vmlinuz-0-rescue-8c51b04886234e47bf5385321ac3bcae
-rwxr-xr-x. 1 root root 5029136 Apr 15  2015 /boot/vmlinuz-0-rescue-f93f471fcefa4190a918621cd9b830e9
-rwxr-xr-x. 1 root root 5393008 Mar  3 08:15 /boot/vmlinuz-3.10.0-514.10.2.el7.x86_64
-rwxr-xr-x. 1 root root 5393328 Dec  7 07:18 /boot/vmlinuz-3.10.0-514.2.2.el7.x86_64
-rwxr-xr-x. 1 root root 6192368 Feb 27 09:45 /boot/vmlinuz-4.10.1-1.el7.elrepo.x86_64

2. 替换CentOS7内核

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

回显结果类似：

CentOS Linux (4.10.1-1.el7.elrepo.x86_64) 7 (Core)
CentOS Linux (4.10.1-1.el7.elrepo.x86_64) 7 (Core) with debugging
CentOS Linux 7 Rescue 56751acc5351469882eb49d16e0d7f16 (3.10.0-514.10.2.el7.x86_64)
CentOS Linux 7 Rescue 56751acc5351469882eb49d16e0d7f16 (3.10.0-514.10.2.el7.x86_64) with debugging
CentOS Linux (3.10.0-514.10.2.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-514.10.2.el7.x86_64) 7 (Core) with debugging
CentOS Linux 7 Rescue 8c51b04886234e47bf5385321ac3bcae (3.10.0-514.2.2.el7.x86_64)
CentOS Linux 7 Rescue 8c51b04886234e47bf5385321ac3bcae (3.10.0-514.2.2.el7.x86_64) with debugging
CentOS Linux (3.10.0-514.2.2.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-514.2.2.el7.x86_64) 7 (Core) with debugging
CentOS Linux 7 (Core), with Linux 0-rescue-f93f471fcefa4190a918621cd9b830e9

grub2-set-default 0，切换到新内核

grub2-set-default 0

重启服务器：

reboot

查看内核版本

uname -a

回显结果类似：

Linux DeterminedJaded-VM 4.10.1-1.el7.elrepo.x86_64 #1 SMP Sun Feb 26 19:47:48 EST 2017 x86_64 x86_64 x86_64 GNU/Linux

3. 开启TCP-BBR

cat >>/etc/sysctl.conf << EOF
net.core.default_qdisc=fq
net.ipv4.tcp_congestion_control=bbr
EOF

内核参数生效：

sysctl -p

回显结果类似：

fs.file-max = 65535
net.ipv4.tcp_max_tw_buckets = 60000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.ipv4.tcp_max_syn_backlog = 65536
net.core.netdev_max_backlog = 32768
net.core.somaxconn = 32768
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_timestamps = 1
net.ipv4.tcp_fin_timeout = 20
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.ip_local_port_range = 1024 65000
net.nf_conntrack_max = 6553500
net.netfilter.nf_conntrack_max = 6553500
net.netfilter.nf_conntrack_tcp_timeout_close_wait = 60
net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 120
net.netfilter.nf_conntrack_tcp_timeout_time_wait = 120
net.netfilter.nf_conntrack_tcp_timeout_established = 3600
net.core.default_qdisc = fq
net.ipv4.tcp_congestion_control = bbr

查看bbr是否生效：

sysctl net.ipv4.tcp_available_congestion_control

回显结果类似：

net.ipv4.tcp_available_congestion_control = bbr cubic reno

 lsmod | grep bbr

回显结果显示：

tcp_bbr                16384  0

至此全部修改结束。

结论

对于与国内连接速度差的vps来说，开启Google TCP-BBR优化算法并没有什么卵用……

本站还架设在OPENVZ构架的RamNode的VPS上，速度明显比Virmach上的快太多了。

以上。