106 lines
3.1 KiB
Markdown
106 lines
3.1 KiB
Markdown
# Google BBR
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Google BBR是一种由Google开发的拥塞控制算法，它能够显著提升服务器吞吐率并降低延迟。
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Google BBR已经被内置于Linux Kernel 4.9及更高版本中，但是需要手动开启。
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关于Google BBR算法，可以在这篇[官方博客](https://cloud.google.com/blog/products/networking/tcp-bbr-congestion-control-comes-to-gcp-your-internet-just-got-faster)或者这个[官方库](https://github.com/google/bbr)中找到更多信息。
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## 准备
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可以通过命令 `uname -r` 来查看当前Linux Kernel版本。版本大于等于4.9时，可以直接参照[下方的说明](#部署google-bbr)部署BBR。
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通常而言，Ubuntu 18.04+, Debian 10+，CentOS 8+及RHEL 8+的内核版本都大于4.9。但是对于CentOS 7或者Amazon Linux 2，需要通过以下的方式更新内核之后才能部署Google BBR。
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### Amazon Linux 2
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Amazon Linux 2提供过经过验证的新版Linux Kernel，并可以通过启用预置的Extras库安装。
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1. 启用 `kernel-ng` Extras 库
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```bash
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sudo amazon-linux-extras install kernel-ng
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```
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2. 更新包
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```bash
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sudo yum update
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```
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3. 重启系统
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```bash
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sudo reboot
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```
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4. 检查Linux Kernel版本
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```bash
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uname -r
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```
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### CentOS 7
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当使用CentOS 7时，需要安装由ELRepo Project提供的新版Linux Kernel。可以在[这个页面](http://elrepo.org/tiki/kernel-ml)找到有关ELRepo Project提供的Linux Kernel的更多信息。
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以下的安装说明，因为缺少可供参考的中文文档，暂仅提供英文版。
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1. Import ELRepo Project's public key.
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```bash
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sudo rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
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```
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2. Install ELRepo for RHEL-7, SL-7 or CentOS-7.
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```bash
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sudo yum install https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
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```
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3. Install `kernel-ml`.
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```bash
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sudo yum --enablerepo=elrepo-kernel install kernel-ml
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```
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4. Confirm the result.
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```bash
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rpm -qa | grep kernel
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```
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You should see `kernel-ml-xxx` in output.
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5. Show all entries in the grub2 menu and setup `kernel-ml`.
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```bash
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sudo egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \'
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```
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**Indexing starts at `0`.**
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For example, when the `kernel-ml` is located at `1`, use the command below to activate `kernel-ml`.
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```bash
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sudo grub2-set-default 1
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```
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6. Reboot.
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```bash
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sudo reboot
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```
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7. Check Linux kernel version.
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```bash
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uname -r
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```
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## 部署Google BBR
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在这个部分，我们将通过修改配置文件启动Google BBR。
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1. 备份 `/etc/sysctl.conf`
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```bash
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sudo cp /etc/sysctl.conf /etc/sysctl.conf.backup
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```
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2. 修改`/etc/sysctl.conf`
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```bash
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sudo vim /etc/sysctl.conf
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```
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在文件中增加以下行
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```
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net.core.default_qdisc = fq
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net.ipv4.tcp_congestion_control = bbr
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```
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3. 启用Google BBR
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```bash
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sudo sysctl -p
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```
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4. 检查Google BBR状态
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```bash
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sudo sysctl net.ipv4.tcp_available_congestion_control
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# net.ipv4.tcp_available_congestion_control = reno cubic bbr
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sudo sysctl -n net.ipv4.tcp_congestion_control
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# bbr
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lsmod | grep bbr
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# tcp_bbr 16384 0
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``` |