使用谷歌的BBR拥塞算法为TCP加速

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BBR简述

Google 开源了其 TCP BBR 拥塞控制算法，并提交到了 Linux 内核，从 4.9 开始，Linux 内核已经用上了该算法。 BBR 算法的目的是要尽量跑满带宽，并且尽量不要有排队的情况。它可以起到单边加速 TCP 连接的效果。

TCP BBR 致力于解决两个问题

  • 在有一定丢包率的网络链路上充分利用带宽
  • 降低网络链路上的 buffer 占用率，从而降低延迟

BBR算法的优势

一键配置脚本

该脚本用于 CentOS 系列 6 和 7 版本的系统，执行后将升级内核并且通过 yum 安装，可能下载较慢，可手动下载 rpm 包

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#!/usr/bin/env bash
:<<:
------------------------------------------------
       FileName : google_bbr_centos.sh
         Author : Silence
    Create Time : 2017-05-09 15:09:16
  Last modified : 2017-11-26 17:56:25
           Mail : 
        Version : 0.0.1
    Description : Auto install latest kernel for TCP BBR
      CopyRight :
------------------------------------------------
:

# Set up a default search path.
PATH="/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin:/root/bin"
export PATH

# Make sure umask is sane
umask 022

# terminal sequence to set color to a 'success' color (currently: green)
SETCOLOR_SUCCESS="echo -en \\033[0;32m"
# terminal sequence to set color to a 'failure' color (currently: red)
SETCOLOR_FAILURE="echo -en \\033[0;31m"
# terminal sequence to set color to a 'warning' color (currently: yellow)
SETCOLOR_WARNING="echo -en \\033[0;33m"
# terminal sequence to reset to the default color.
SETCOLOR_NORMAL="echo -en \\033[0;39m"

# Log that something succeeded
echo_info(){
    echo -en "[ ";
    ${SETCOLOR_SUCCESS};
    echo -en " Info ";
    ${SETCOLOR_NORMAL};
    echo -en " ]  ";
    echo "$@"
}
# Log that something Error
echo_error(){
    echo -en "[ ";
    ${SETCOLOR_FAILURE};
    echo -en " Error ";
    ${SETCOLOR_NORMAL};
    echo -en " ]  ";
    echo "$@"
}
# Log a warning
echo_warning(){
    echo -en "[ ";
    ${SETCOLOR_WARNING};
    echo -en " Warning ";
    ${SETCOLOR_NORMAL};
    echo -en " ]  ";
    echo "$@"
}

bbr_sysctl_config(){
    sed -i '/net.core.default_qdisc/d' /etc/sysctl.conf
    sed -i '/net.ipv4.tcp_congestion_control/d' /etc/sysctl.conf
    echo "net.core.default_qdisc = fq" >> /etc/sysctl.conf
    echo "net.ipv4.tcp_congestion_control = bbr" >> /etc/sysctl.conf
    sysctl -p >/dev/null 2>&1
}

get_os() {
    [ -f /etc/redhat-release ] && awk '{print ($1,$3~/^[0-9]/?$3:$4)}' /etc/redhat-release && return
    [ -f /etc/os-release ] && awk -F'[= "]' '/PRETTY_NAME/{print $3,$4,$5}' /etc/os-release && return
    [ -f /etc/lsb-release ] && awk -F'[="]+' '/DESCRIPTION/{print $2}' /etc/lsb-release && return
}

get_char() {
    SAVEDSTTY=`stty -g`
    stty -echo
    stty cbreak
    dd if=/dev/tty bs=1 count=1 2> /dev/null
    stty -raw
    stty echo
    stty $SAVEDSTTY
}

clear
echo "------------- System Information --------------"
echo
echo "          OS : $(get_os)"
echo "        Arch : $(uname -m) $(getconf LONG_BIT) Bit"
echo "      Kernel : $(uname -r)"
echo
echo "-----------------------------------------------"
echo " Auto upgrade latest kernel and turn on TCP BBR"
echo "-----------------------------------------------"
echo
echo "Press any key to start...or Press Ctrl+C to cancel"
char=$(get_char)
echo


#------------------------------------------------
# Test the operator is root or not
#------------------------------------------------
if test "${EUID}" -ne 0 -o "${USER}" != "root";then
    echo_error "Only root can run this script ... "
    exit 5
else
    echo_info "Operator is root "
fi
#************************************************


#------------------------------------------------  
# Check network is rechable or not
#------------------------------------------------
dstname="www.baidu.com"
if (ping ${dstname} -c 3 -i 0.01 -w 2 -q 1>/dev/null 2>&1)then
    echo_info "Network is rechable "
else
    RETVAL=$?
    echo_error "Network is unreachable , please check "
    exit 5
fi
#************************************************


#------------------------------------------------
# Check your OS is Redhat release or not 
#------------------------------------------------
rla="$(egrep -i "centos|red hat|redhat" /etc/issue)"
rlb="$(egrep -i "centos|red hat|redhat" /proc/version)"
if [ -f /etc/centos-release -o -n "${rla}" -o -n "${rlb}" ]; then
    echo_info "OS is Redhat release" 
else
    echo_error "Only support for CentOS"
    exit 5
fi
#************************************************


#------------------------------------------------
# Check bbr status
#------------------------------------------------
conGestion="$(set -- $(sysctl -n net.ipv4.tcp_available_congestion_control);echo $1)"
# Get the congestion_control from Kernel parameter
bbrmodules="$(lsmod | fgrep tcp_bbr)"
# Show the status of tcp_bbr module in the Linux Kernel
if [ "${conGestion}" = "bbr" -a -n "${bbrmodules}" ];then
    echo_info "TCP BBR has been installed. Nothing to do..."
    exit 5
fi
#************************************************


#------------------------------------------------
# Check version of kernel is newer or not
#------------------------------------------------
kernelRelease="$(uname -r)"
newORold=$(set -- ${kernelRelease%%-*} 4.9;test "$(echo -e "$1\n$2" | sort -rV | head -1)" == "$1" && echo newer || echo older )
if test "${newORold}" == 'newer';then
    echo_info "Version of your kernel is greater than 4.9 , directly setting TCP BBR..."
    bbr_sysctl_config
    echo_info "Setting TCP BBR ..."
    echo_info 'Complete ! '
    exit 5
fi
#************************************************


#------------------------------------------------
# Install elrepo
#------------------------------------------------
OS_X="`grep -Po '(?<=\brelease )[\d]' /etc/redhat-release`"
if test ! -z "${OS_X//[0-9]/}";then
    echo_error "Not available for your system :("
else
    echo_info "Installing elrepo"
fi

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
case $OS_X in
    6)
        rpm -Uvh http://www.elrepo.org/elrepo-release-6-8.el6.elrepo.noarch.rpm
        ;;
    7)
        rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
        ;;
    *)
        echo_error "Not support for CentOS${OS_X}"
        exit 5
        ;;
esac

if [ ! -s /etc/yum.repos.d/elrepo.repo ]; then
    echo_error "Install elrepo failed , please check "
    exit 5
fi
#************************************************


#------------------------------------------------
# Upgrade kernel
#------------------------------------------------
yum --enablerepo=elrepo-kernel -y install kernel-ml kernel-ml-devel

echo_info "Query package :"
echo '------------------------------------------------'
rpm -qa kernel-ml
echo '------------------------------------------------'
echo
if [ $? -ne 0 ]; then
    echo_error "Install latest kernel failed, please check it."
    exit 5
fi
#************************************************


#------------------------------------------------
# config for grub
#------------------------------------------------
case $OS_X in
    6)
        if [ ! -s "/boot/grub/grub.conf" ]; then
            echo_error "/boot/grub/grub.conf wrong, please check it."
            exit 5
        fi

        echo_info "List of kernel that is available"
        echo '------------------------------------------------'
        awk '/title/{$1="";print}' /etc/grub.conf
        echo '------------------------------------------------'
        echo 

        sed -ri 's/^default=.*/default=0/g' /boot/grub/grub.conf
        ;;
    7)
        if [ ! -s "/boot/grub2/grub.cfg" ]; then
            echo_error "/boot/grub2/grub.cfg wrong, please check it."
            exit 5
        fi

        echo_info "List of kernel that is available"
        echo '------------------------------------------------'
        awk -F'[\047]+'  '/^menuentry/{print $2}' /boot/grub2/grub.cfg
        echo '------------------------------------------------'
        echo

        grub_default_kernel=$(awk -F'[\047]+'  '/^menuentry/{print "\047"$2"\047";exit}' /boot/grub2/grub.cfg)
        
        echo "grub2-set-default 0"
        echo
        grub2-set-default 0

        echo "grub2-mkconfig -o /boot/grub2/grub.cfg"
        echo
        grub2-mkconfig -o /boot/grub2/grub.cfg
        ;;
    *)
        echo_error "Not support for CentOS${OS_X}"
        exit 5
        ;;
esac
#************************************************

bbr_sysctl_config

#------------------------------------------------
# Waitting for reboot
#------------------------------------------------
echo
echo_warning "The system needs to reboot."
echo 
read -p 'Do you want to restart system ? [yes/no] ' yesOrno
case "${yesOrno}" in
    y|Y|[yY][eE]|[yY][eE][sS])
            reboot
            echo "Reboot test"
            ;;
    n|N|[nN][oO])
            echo_info "Reboot has been canceled..."
            exit 5
            ;;
esac
#************************************************

参考命令

查看内核模块的信息

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modinfo tcp_bbr

查看可用内核 

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awk -F'[\047]+'  '/^menuentry/{print $2}' /boot/grub2/grub.cfg

查看当前内核的版本

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uname -r

修改开机时默认使用的内核

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grub2-set-default 'CentOS Linux (4.14.2-1.el7.elrepo.x86_64) 7 (Core)'
# 或使用索引号0、1、2.....
grub2-set-default 0

查看内核修改结果

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grub2-editenv list

重新生成 grub2 的配置文件

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

GRUB 2 操作帮助： http://fedoraproject.org/wiki/GRUB_2/zh-cn

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