From afef8bf22369d10ab8107a63b1e3529ed7dd6c8d Mon Sep 17 00:00:00 2001 From: Florin Coras Date: Wed, 11 Sep 2019 23:22:29 -0700 Subject: [PATCH] tcp: refactor congestion event handling Type: refactor Minor cleanup to congestion event handling. Change-Id: I7179ff9e21c1853382ba814652c9024f3e5b8a37 Signed-off-by: Florin Coras --- src/vnet/tcp/tcp_input.c | 76 +++++++++++++++++++++++------------------------- 1 file changed, 36 insertions(+), 40 deletions(-) diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c index ad937e90438..933f913bc5a 100755 --- a/src/vnet/tcp/tcp_input.c +++ b/src/vnet/tcp/tcp_input.c @@ -614,10 +614,8 @@ tcp_handle_postponed_dequeues (tcp_worker_ctx_t * wrk) * otherwise update. */ tcp_retransmit_timer_update (tc); - /* If not congested, update pacer based on our new - * cwnd estimate */ - if (!tcp_in_fastrecovery (tc)) - tcp_connection_tx_pacer_update (tc); + /* Update pacer based on our new cwnd estimate */ + tcp_connection_tx_pacer_update (tc); } _vec_len (wrk->pending_deq_acked) = 0; } @@ -1375,34 +1373,46 @@ static void tcp_cc_handle_event (tcp_connection_t * tc, tcp_rate_sample_t * rs, u32 is_dack) { - u32 rxt_delivered; + u8 has_sack = tcp_opts_sack_permitted (&tc->rcv_opts); - if (tcp_in_fastrecovery (tc) && tcp_opts_sack_permitted (&tc->rcv_opts)) + /* + * Already in fast recovery. Return if no data acked, partial acks + * and accounting for segments that have left the network are done + * lower. + */ + if (tcp_in_fastrecovery (tc)) { - if (tc->bytes_acked) - goto partial_ack; - tcp_program_fastretransmit (tc); - return; + if (!has_sack) + tc->rcv_dupacks++; + + if (!tc->bytes_acked) + { + tcp_program_fastretransmit (tc); + if (!has_sack) + tcp_cc_rcv_cong_ack (tc, TCP_CC_DUPACK, rs); + return; + } + } + /* + * In timer triggered recovery + */ + else if (tcp_in_recovery (tc)) + { + /* No fast recovery entry at this point */ + if (!tc->bytes_acked) + return; } /* - * Duplicate ACK. Check if we should enter fast recovery, or if already in - * it account for the bytes that left the network. + * Duplicate ACK. Check if we should enter fast recovery */ - else if (is_dack && !tcp_in_recovery (tc)) + else if (is_dack) { TCP_EVT (TCP_EVT_DUPACK_RCVD, tc, 1); ASSERT (tc->snd_una != tc->snd_nxt || tc->sack_sb.last_sacked_bytes); tc->rcv_dupacks++; - /* Pure duplicate ack. If some data got acked, it's handled lower */ - if (tc->rcv_dupacks > TCP_DUPACK_THRESHOLD && !tc->bytes_acked) - { - ASSERT (tcp_in_fastrecovery (tc)); - tcp_cc_rcv_cong_ack (tc, TCP_CC_DUPACK, rs); - return; - } - else if (tcp_should_fastrecover (tc)) + if (tcp_should_fastrecover (tc)) { u32 pacer_wnd; @@ -1419,7 +1429,7 @@ tcp_cc_handle_event (tcp_connection_t * tc, tcp_rate_sample_t * rs, tcp_cc_init_congestion (tc); - if (tcp_opts_sack_permitted (&tc->rcv_opts)) + if (has_sack) scoreboard_init_high_rxt (&tc->sack_sb, tc->snd_una); /* Constrain rate until we get a partial ack */ @@ -1429,14 +1439,11 @@ tcp_cc_handle_event (tcp_connection_t * tc, tcp_rate_sample_t * rs, tcp_program_fastretransmit (tc); return; } - else if (!tc->bytes_acked - || (tc->bytes_acked && !tcp_in_cong_recovery (tc))) + else { tcp_cc_rcv_cong_ack (tc, TCP_CC_DUPACK, rs); return; } - else - goto partial_ack; } /* Don't allow entry in fast recovery if still in recovery, for now */ else if (0 && is_dack && tcp_in_recovery (tc)) @@ -1461,24 +1468,15 @@ tcp_cc_handle_event (tcp_connection_t * tc, tcp_rate_sample_t * rs, } } - if (!tc->bytes_acked) - return; - -partial_ack: + ASSERT (tc->bytes_acked); TCP_EVT (TCP_EVT_CC_PACK, tc); /* * Legitimate ACK. 1) See if we can exit recovery */ - /* Update the pacing rate. For the first partial ack we move from - * the artificially constrained rate to the one after congestion */ - tcp_connection_tx_pacer_update (tc); - if (seq_geq (tc->snd_una, tc->snd_congestion)) { - tcp_retransmit_timer_update (tc); - /* If spurious return, we've already updated everything */ if (tcp_cc_recover (tc)) { @@ -1495,9 +1493,6 @@ partial_ack: * Legitimate ACK. 2) If PARTIAL ACK try to retransmit */ - /* XXX limit this only to first partial ack? */ - tcp_retransmit_timer_update (tc); - /* RFC6675: If the incoming ACK is a cumulative acknowledgment, * reset dupacks to 0. Also needed if in congestion recovery */ tc->rcv_dupacks = 0; @@ -1511,7 +1506,7 @@ partial_ack: } /* Remove retransmitted bytes that have been delivered */ - if (tcp_opts_sack_permitted (&tc->rcv_opts)) + if (has_sack) { ASSERT (tc->bytes_acked >= tc->sack_sb.last_bytes_delivered || (tc->flags & TCP_CONN_FINSNT)); @@ -1520,6 +1515,7 @@ partial_ack: * remove sacked bytes delivered */ if (seq_lt (tc->snd_una, tc->sack_sb.high_rxt)) { + u32 rxt_delivered; rxt_delivered = tc->bytes_acked - tc->sack_sb.last_bytes_delivered; ASSERT (tc->snd_rxt_bytes >= rxt_delivered); tc->snd_rxt_bytes -= rxt_delivered; -- 2.16.6