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authorYuchung Cheng <ycheng@google.com>2017-01-12 22:11:39 -0800
committerDavid S. Miller <davem@davemloft.net>2017-01-13 22:37:16 -0500
commitbec41a11dd3dc8c54f766b4f494140ca92ba7c10 (patch)
tree62a888654cc55636c2ab85adf331db2361aae118 /net/ipv4/tcp_output.c
parent840a3cbe89694fad75578856976f180e852e69aa (diff)
downloadlinux-bec41a11dd3dc8c54f766b4f494140ca92ba7c10.tar.bz2
tcp: remove early retransmit
This patch removes the support of RFC5827 early retransmit (i.e., fast recovery on small inflight with <3 dupacks) because it is subsumed by the new RACK loss detection. More specifically when RACK receives DUPACKs, it'll arm a reordering timer to start fast recovery after a quarter of (min)RTT, hence it covers the early retransmit except RACK does not limit itself to specific inflight or dupack numbers. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_output.c')
-rw-r--r--net/ipv4/tcp_output.c11
1 files changed, 4 insertions, 7 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 6327e4d368a4..9a1a1494b9dd 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -76,10 +76,8 @@ static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
tp->snd_nxt = TCP_SKB_CB(skb)->end_seq;
tp->packets_out += tcp_skb_pcount(skb);
- if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
- icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
+ if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
tcp_rearm_rto(sk);
- }
NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT,
tcp_skb_pcount(skb));
@@ -2289,8 +2287,6 @@ bool tcp_schedule_loss_probe(struct sock *sk)
u32 timeout, tlp_time_stamp, rto_time_stamp;
u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3);
- if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS))
- return false;
/* No consecutive loss probes. */
if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) {
tcp_rearm_rto(sk);
@@ -2309,8 +2305,9 @@ bool tcp_schedule_loss_probe(struct sock *sk)
/* Schedule a loss probe in 2*RTT for SACK capable connections
* in Open state, that are either limited by cwnd or application.
*/
- if (sysctl_tcp_early_retrans < 3 || !tp->packets_out ||
- !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open)
+ if ((sysctl_tcp_early_retrans != 3 && sysctl_tcp_early_retrans != 4) ||
+ !tp->packets_out || !tcp_is_sack(tp) ||
+ icsk->icsk_ca_state != TCP_CA_Open)
return false;
if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) &&