tcp: use sequence distance to detect reordering

Replace the reordering distance measurement in packet unit with
sequence based approach. Previously it trackes the number of "packets"
toward the forward ACK (i.e.  highest sacked sequence)in a state
variable "fackets_out".

Precisely measuring reordering degree on packet distance has not much
benefit, as the degree constantly changes by factors like path, load,
and congestion window. It is also complicated and prone to arcane bugs.
This patch replaces with sequence-based approach that's much simpler.

Signed-off-by: Yuchung Cheng <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Reviewed-by: Neal Cardwell <[email protected]>
Reviewed-by: Soheil Hassas Yeganeh <[email protected]>
Reviewed-by: Priyaranjan Jha <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

1 files changed, 0 insertions, 1 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 337555076043..bf97317e6c97 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2977,7 +2977,6 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 
 	info->tcpi_lost = tp->lost_out;
 	info->tcpi_retrans = tp->retrans_out;
-	info->tcpi_fackets = tp->fackets_out;
 
 	now = tcp_jiffies32;
 	info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);