tcp: prefer packet timing to TS-ECR for RTT
authorYuchung Cheng <ycheng@google.com>
Mon, 22 Jul 2013 23:20:46 +0000 (16:20 -0700)
committerDavid S. Miller <davem@davemloft.net>
Tue, 23 Jul 2013 00:53:42 +0000 (17:53 -0700)
commit5b08e47caf1f2034a3a5b566bbccc8b0be3961ca
tree5cdd3ad01a4b854c80bad612051ac7ce7140e948
parent375fe02c91792917aa26d68a87ab110d1937f44e
tcp: prefer packet timing to TS-ECR for RTT

Prefer packet timings to TS-ecr for RTT measurements when both
sources are available. That's because broken middle-boxes and remote
peer can return packets with corrupted TS ECR fields. Similarly most
congestion controls that require RTT signals favor timing-based
sources as well. Also check for bad TS ECR values to avoid RTT
blow-ups. It has happened on production Web servers.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/tcp.h
net/ipv4/tcp_input.c