Why we standardized on BBR for every server we deploy

Linux kernel 4.9+ ships with BBR. We turned it on across our fleet and measured the impact.

What changed

net.core.default_qdisc = fq
net.ipv4.tcp_congestion_control = bbr

Results

Throughput on transatlantic flows: +35%. Time-to-first-byte unchanged. No regression on local LAN traffic.