tcp_bbr: init pacing rate on first RTT sample
authorNeal Cardwell <ncardwell@google.com>
Fri, 14 Jul 2017 21:49:25 +0000 (17:49 -0400)
committerDavid S. Miller <davem@davemloft.net>
Sat, 15 Jul 2017 21:43:29 +0000 (14:43 -0700)
commit32984565574da7ed3afa10647bb4020d7a9e6c93
tree7dff690c6f1db2ff2a00d0b1f1b824901aeb6c6c
parent1d3648eb5d1fe9ed3d095ed8fa19ad11ca4c8bc0
tcp_bbr: init pacing rate on first RTT sample

Fixes the following behavior: for connections that had no RTT sample
at the time of initializing congestion control, BBR was initializing
the pacing rate to a high nominal rate (based an a guess of RTT=1ms,
in case this is LAN traffic). Then BBR never adjusted the pacing rate
downward upon obtaining an actual RTT sample, if the connection never
filled the pipe (e.g. all sends were small app-limited writes()).

This fix adjusts the pacing rate upon obtaining the first RTT sample.

Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/tcp_bbr.c