From 3af90fceb61d0c236709c25df936bbbf304cbff5 Mon Sep 17 00:00:00 2001 From: Florin Coras Date: Wed, 3 May 2017 21:09:42 -0700 Subject: Fix TCP loss recovery, VPP-745 Allows pure loss recovery retransmits only on timeout. Change-Id: I563cdbf9e7b890a6569350bdbda4f746ace0544e Signed-off-by: Florin Coras --- src/vnet/tcp/tcp_input.c | 35 +++++++++++++++++++++++++---------- 1 file changed, 25 insertions(+), 10 deletions(-) (limited to 'src/vnet/tcp/tcp_input.c') diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c index 0030cfe2..e9c52c5e 100644 --- a/src/vnet/tcp/tcp_input.c +++ b/src/vnet/tcp/tcp_input.c @@ -392,11 +392,10 @@ tcp_update_rtt (tcp_connection_t * tc, u32 ack) /* Karn's rule, part 1. Don't use retransmitted segments to estimate * RTT because they're ambiguous. */ - if (tc->rtt_seq && seq_gt (ack, tc->rtt_seq) && !tc->rto_boff) + if (tc->rtt_ts && seq_geq (ack, tc->rtt_seq) && !tc->rto_boff) { mrtt = tcp_time_now () - tc->rtt_ts; } - /* As per RFC7323 TSecr can be used for RTTM only if the segment advances * snd_una, i.e., the left side of the send window: * seq_lt (tc->snd_una, ack). Note: last condition could be dropped, we don't @@ -406,19 +405,22 @@ tcp_update_rtt (tcp_connection_t * tc, u32 ack) mrtt = tcp_time_now () - tc->opt.tsecr; } + /* Allow measuring of a new RTT */ + tc->rtt_ts = 0; + + /* If ACK moves left side of the wnd make sure boff is 0, even if mrtt is + * not valid */ + if (tc->bytes_acked) + tc->rto_boff = 0; + /* Ignore dubious measurements */ if (mrtt == 0 || mrtt > TCP_RTT_MAX) return 0; tcp_estimate_rtt (tc, mrtt); - tc->rto = clib_min (tc->srtt + (tc->rttvar << 2), TCP_RTO_MAX); - /* Allow measuring of RTT and make sure boff is 0 */ - tc->rtt_seq = 0; - tc->rto_boff = 0; - - return 1; + return 0; } /** @@ -735,7 +737,7 @@ tcp_cc_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b) { u8 partial_ack; - if (tcp_in_cong_recovery (tc)) + if (tcp_in_fastrecovery (tc)) { partial_ack = seq_lt (tc->snd_una, tc->snd_congestion); if (!partial_ack) @@ -749,6 +751,7 @@ tcp_cc_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b) /* Clear retransmitted bytes. XXX should we clear all? */ tc->rtx_bytes = 0; + tc->cc_algo->rcv_cong_ack (tc, TCP_CC_PARTIALACK); /* In case snd_nxt is still in the past and output tries to @@ -772,6 +775,13 @@ tcp_cc_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b) tc->cc_algo->rcv_ack (tc); tc->tsecr_last_ack = tc->opt.tsecr; tc->rcv_dupacks = 0; + if (tcp_in_recovery (tc)) + { + tc->rtx_bytes -= clib_min (tc->bytes_acked, tc->rtx_bytes); + tc->rto = clib_min (tc->srtt + (tc->rttvar << 2), TCP_RTO_MAX); + if (seq_geq (tc->snd_una, tc->snd_congestion)) + tcp_recovery_off (tc); + } } } @@ -897,7 +907,7 @@ tcp_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b, tcp_cc_rcv_ack (tc, b); /* If everything has been acked, stop retransmit timer - * otherwise update */ + * otherwise update. */ if (tc->snd_una == tc->snd_una_max) tcp_retransmit_timer_reset (tc); else @@ -1778,6 +1788,11 @@ tcp46_rcv_process_inline (vlib_main_t * vm, vlib_node_runtime_t * node, tcp_send_reset (b0, is_ip4); goto drop; } + + /* Update rtt and rto */ + tc0->bytes_acked = 1; + tcp_update_rtt (tc0, vnet_buffer (b0)->tcp.ack_number); + /* Switch state to ESTABLISHED */ tc0->state = TCP_STATE_ESTABLISHED; -- cgit 1.2.3-korg