120 lines
3.7 KiB
Markdown
120 lines
3.7 KiB
Markdown
[English](bbr.md) | [中文](bbr-zh.md)
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# Advanced usage: Deploy Google BBR congestion control algorithm
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Google BBR is a congestion control algorithm that could significantly increase server throughput and reduce latency.
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Google BBR has been built into Linux kernel 4.9 and higher, but needs to be manually turned on.
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To learn more about the Google BBR algorithm, see this [official blog](https://cloud.google.com/blog/products/networking/tcp-bbr-congestion-control-comes-to-gcp-your-internet-just-got-faster) or this [official repository](https://github.com/google/bbr).
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## Prepare
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You can check the current Linux kernel version with the command `uname -r`. When the version is greater than or equal to 4.9, you can deploy BBR directly by referring to the [instructions below](#deploy-google-bbr).
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Generally speaking, the kernel versions of Ubuntu 18.04+, Debian 10+, CentOS 8+ and RHEL 8+ are greater than 4.9. But for CentOS 7 or Amazon Linux 2, you need to update the kernel in the following ways before deploying Google BBR.
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### Amazon Linux 2
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Amazon Linux 2 provides newer versions of the verified Linux kernel, which can be installed from the Extras repository.
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1. Install `kernel-ng` from the Extras repository
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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. Update packages
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```bash
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sudo yum update
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```
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3. Restart the system
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```bash
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sudo reboot
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```
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4. Check the Linux kernel version
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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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When using CentOS 7, a newer Linux kernel provided by the ELRepo Project needs to be installed. More information about the Linux kernels provided by the ELRepo Project can be found at [this page](http://elrepo.org/tiki/kernel-ml).
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Refer to the installation instructions below.
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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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## Deploy Google BBR
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In this section, we will start Google BBR by modifying the configuration file.
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1. Backup `/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. Modify `/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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Add the following lines to the file
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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. Enable Google BBR
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First, check your server's kernel version using `uname -r`.
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For kernel versions >= 4.20, apply `sysctl` settings:
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```bash
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sudo sysctl -p
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```
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For kernel versions < 4.20, you must reboot the server:
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```bash
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sudo reboot
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```
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4. Check Google BBR status
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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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```
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## Document author
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Copyright (C) 2022 [Leo Liu](https://github.com/optimusleobear)
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Translated by [Lin Song](https://github.com/hwdsl2)
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