tcp_early_retrans

file: /proc/sys/net/ipv4/tcp_early_retrans
variable: net.ipv4.tcp_early_retrans
Official reference

Tail loss probe (TLP) converts RTOs occurring due to tail losses into fast recovery (draft-ietf-tcpm-rack). Note that TLP requires RACK to function properly (see tcp_recovery below) Possible values: 0 disables TLP 3 or 4 enables TLP Default: 3

source