Linux启用bbr阻塞控制算法

博主作为Google的一名忠实粉丝，一定不能错过Google开发的任何一样产品啦。

接下来是简单的介绍：

TCP BBR

Funny^{[according to whom?]} comic strips with two developers implement BBR in the hope to replace all other 12 algorithms already available in Linux. But finally BBR is not the best in all the cases, and we have to deal with 13 different algorithms.

Bottleneck Bandwidth and Round-trip propagation time (BBR) is a TCP congestion control algorithm developed at Google^[20] in 2016. While most congestion control algorithms are loss-based, in that they rely on packet loss as a signal to lower rates of transmission, BBR is model-based. The algorithm uses the maximum bandwidth and round-trip time at which the network delivered the most recent flight of outbound data packets to build an explicit model of the network. Each cumulative or selective acknowledgment of packet delivery produces a rate sample which records the amount of data delivered over the time interval between the transmission of a data packet and the acknowledgment of that packet.^[21] As network interface controllers evolve from megabit per second to gigabit per second performance,^{[clarification needed]} packet loss should no longer be considered the primary determining factor in identifying congestion, making model-based congestion control algorithms which provide higher throughput and lower latency, such as BBR, a more reliable alternative to more popular algorithms like CUBIC.

When implemented within YouTube, BBR yielded an average of 4% higher network throughput and up to 14% in some countries.^[22]

BBR is also available for QUIC and Linux TCP in Linux 4.9.^[23][24]

According to Geoff Huston ^[25] BBR is efficient and fast, but highly unfair to other, non-BBR streams. He calls it “not scalable” and says it “has the ability to slaughter concurrent loss-based flows”. Hock, Bless and Zitterbart ^[26] evaluated BBR’s implementation in Linux 4.9. If used with one flow, they confirmed the claimed features, but also found “some severe inherent issues such as increased queuing delays, unfairness, and massive packet loss”.

接下来是开启的方法：

echo "net.ipv4.tcp_congestion_control=bbr" >> /etc/sysctl.conf
sysctl -pCode language: JavaScript (javascript)

检测是否成功启用的方法：

sysctl net.ipv4.tcp_available_congestion_control
lsmod | grep bbr