diff options
| -rw-r--r-- | include/linux/tcp.h | 3 | ||||
| -rw-r--r-- | include/net/tcp.h | 3 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 69 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 5 | ||||
| -rw-r--r-- | net/ipv4/tcp_timer.c | 5 |
5 files changed, 74 insertions, 11 deletions
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) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e042cab..7096790 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2344,6 +2344,27 @@ static inline int tcp_dupack_heuristics(const struct tcp_sock *tp) return tcp_is_fack(tp) ? tp->fackets_out : tp->sacked_out + 1; } +static bool tcp_pause_early_retransmit(struct sock *sk, int flag) +{ + struct tcp_sock *tp = tcp_sk(sk); + unsigned long delay; + + /* Delay early retransmit and entering fast recovery for + * max(RTT/4, 2msec) unless ack has ECE mark, no RTT samples + * available, or RTO is scheduled to fire first. + */ + if (sysctl_tcp_early_retrans < 2 || (flag & FLAG_ECE) || !tp->srtt) + return false; + + delay = max_t(unsigned long, (tp->srtt >> 5), msecs_to_jiffies(2)); + if (!time_after(inet_csk(sk)->icsk_timeout, (jiffies + delay))) + return false; + + inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, delay, TCP_RTO_MAX); + tp->early_retrans_delayed = 1; + return true; +} + static inline int tcp_skb_timedout(const struct sock *sk, const struct sk_buff *skb) { @@ -2451,7 +2472,7 @@ static inline int tcp_head_timedout(const struct sock *sk) * Main question: may we further continue forward transmission * with the same cwnd? */ -static int tcp_time_to_recover(struct sock *sk) +static int tcp_time_to_recover(struct sock *sk, int flag) { struct tcp_sock *tp = tcp_sk(sk); __u32 packets_out; @@ -2505,7 +2526,7 @@ static int tcp_time_to_recover(struct sock *sk) if (tp->do_early_retrans && !tp->retrans_out && tp->sacked_out && (tp->packets_out == (tp->sacked_out + 1) && tp->packets_out < 4) && !tcp_may_send_now(sk)) - return 1; + return !tcp_pause_early_retransmit(sk, flag); return 0; } @@ -3172,7 +3193,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked, if (icsk->icsk_ca_state <= TCP_CA_Disorder) tcp_try_undo_dsack(sk); - if (!tcp_time_to_recover(sk)) { + if (!tcp_time_to_recover(sk, flag)) { tcp_try_to_open(sk, flag); return; } @@ -3271,16 +3292,47 @@ static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) /* Restart timer after forward progress on connection. * RFC2988 recommends to restart timer to now+rto. */ -static void tcp_rearm_rto(struct sock *sk) +void tcp_rearm_rto(struct sock *sk) { - const struct tcp_sock *tp = tcp_sk(sk); + struct tcp_sock *tp = tcp_sk(sk); if (!tp->packets_out) { inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); } else { - inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, - inet_csk(sk)->icsk_rto, TCP_RTO_MAX); + u32 rto = inet_csk(sk)->icsk_rto; + /* Offset the time elapsed after installing regular RTO */ + if (tp->early_retrans_delayed) { + struct sk_buff *skb = tcp_write_queue_head(sk); + const u32 rto_time_stamp = TCP_SKB_CB(skb)->when + rto; + s32 delta = (s32)(rto_time_stamp - tcp_time_stamp); + /* delta may not be positive if the socket is locked + * when the delayed ER timer fires and is rescheduled. + */ + if (delta > 0) + rto = delta; + } + inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto, + TCP_RTO_MAX); } + tp->early_retrans_delayed = 0; +} + +/* This function is called when the delayed ER timer fires. TCP enters + * fast recovery and performs fast-retransmit. + */ +void tcp_resume_early_retransmit(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + + tcp_rearm_rto(sk); + + /* Stop if ER is disabled after the delayed ER timer is scheduled */ + if (!tp->do_early_retrans) + return; + + tcp_enter_recovery(sk, false); + tcp_update_scoreboard(sk, 1); + tcp_xmit_retransmit_queue(sk); } /* If we get here, the whole TSO packet has not been acked. */ @@ -3729,6 +3781,9 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) if (after(ack, tp->snd_nxt)) goto invalid_ack; + if (tp->early_retrans_delayed) + tcp_rearm_rto(sk); + if (after(ack, prior_snd_una)) flag |= FLAG_SND_UNA_ADVANCED; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 834e89f..d947330 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -78,9 +78,8 @@ static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb) tp->frto_counter = 3; tp->packets_out += tcp_skb_pcount(skb); - if (!prior_packets) - inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, - inet_csk(sk)->icsk_rto, TCP_RTO_MAX); + if (!prior_packets || tp->early_retrans_delayed) + tcp_rearm_rto(sk); } /* SND.NXT, if window was not shrunk. diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 34d4a02..e911e6c 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -319,6 +319,11 @@ void tcp_retransmit_timer(struct sock *sk) struct tcp_sock *tp = tcp_sk(sk); struct inet_connection_sock *icsk = inet_csk(sk); + if (tp->early_retrans_delayed) { + tcp_resume_early_retransmit(sk); + return; + } + if (!tp->packets_out) goto out; |
