From 750ea2bafa55aaed208b2583470ecd7122225634 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Wed, 2 May 2012 13:30:04 +0000 Subject: tcp: early retransmit: delayed fast retransmit Implementing the advanced early retransmit (sysctl_tcp_early_retrans==2). Delays the fast retransmit by an interval of RTT/4. We borrow the RTO timer to implement the delay. If we receive another ACK or send a new packet, the timer is cancelled and restored to original RTO value offset by time elapsed. When the delayed-ER timer fires, we enter fast recovery and perform fast retransmit. Signed-off-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- include/linux/tcp.h | 3 ++- include/net/tcp.h | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 7859b41..d9b42c5be 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -372,7 +372,8 @@ struct tcp_sock { repair : 1, unused : 1; u8 repair_queue; - u8 do_early_retrans:1;/* Enable RFC5827 early-retransmit */ + u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */ + early_retrans_delayed:1; /* Delayed ER timer installed */ /* RTT measurement */ u32 srtt; /* smoothed round trip time << 3 */ diff --git a/include/net/tcp.h b/include/net/tcp.h index 685437a..5283aa4 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -500,6 +500,8 @@ extern void tcp_send_delayed_ack(struct sock *sk); /* tcp_input.c */ extern void tcp_cwnd_application_limited(struct sock *sk); +extern void tcp_resume_early_retransmit(struct sock *sk); +extern void tcp_rearm_rto(struct sock *sk); /* tcp_timer.c */ extern void tcp_init_xmit_timers(struct sock *); @@ -805,6 +807,7 @@ static inline void tcp_enable_early_retrans(struct tcp_sock *tp) { tp->do_early_retrans = sysctl_tcp_early_retrans && !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3; + tp->early_retrans_delayed = 0; } static inline void tcp_disable_early_retrans(struct tcp_sock *tp) -- cgit v1.1