tcp: instrument how long TCP is busy sending
authorFrancis Yan <francisyyan@gmail.com>
Mon, 28 Nov 2016 07:07:14 +0000 (23:07 -0800)
committerDavid S. Miller <davem@davemloft.net>
Wed, 30 Nov 2016 15:04:24 +0000 (10:04 -0500)
commit0f87230d1a6c253681550c6064715d06a32be73d
tree592c761f9b1b2b6e524e8fc87a43db69ded5e4a8
parent05b055e89121394058c75dc354e9a46e1e765579
tcp: instrument how long TCP is busy sending

This patch measures TCP busy time, which is defined as the period
of time when sender has data (or FIN) to send. The time starts when
data is buffered and stops when the write queue is flushed by ACKs
or error events.

Note the busy time does not include SYN time, unless data is
included in SYN (i.e. Fast Open). It does include FIN time even
if the FIN carries no payload. Excluding pure FIN is possible but
would incur one additional test in the fast path, which may not
be worth it.

Signed-off-by: Francis Yan <francisyyan@gmail.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@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
net/ipv4/tcp_output.c