From bec41a11dd3dc8c54f766b4f494140ca92ba7c10 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Thu, 12 Jan 2017 22:11:39 -0800 Subject: 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 Signed-off-by: Neal Cardwell Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'net/ipv4/tcp_output.c') 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)) && -- cgit v1.2.3