From c31dc31f84961033ecb6354811e0c360b6cf5f79 Mon Sep 17 00:00:00 2001 From: Florin Coras Date: Sun, 6 Oct 2019 14:06:14 -0700 Subject: tcp: improve pacing after idle send periods Rest pacer on ack reception if we haven't recently sent anything. Type: feature Change-Id: I820bacd81b65130052dfafbfcbe6ca4553069fbc Signed-off-by: Florin Coras --- src/vnet/tcp/tcp_output.c | 113 ++++++++++++++++++++++++++-------------------- 1 file changed, 65 insertions(+), 48 deletions(-) (limited to 'src/vnet/tcp/tcp_output.c') diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c index 79866aff03a..047247e9ebe 100644 --- a/src/vnet/tcp/tcp_output.c +++ b/src/vnet/tcp/tcp_output.c @@ -409,7 +409,10 @@ tcp_update_burst_snd_vars (tcp_connection_t * tc) tc->flags |= TCP_CONN_TRACK_BURST; if (tc->snd_una == tc->snd_nxt) - tcp_cc_event (tc, TCP_CC_EVT_START_TX); + { + tcp_cc_event (tc, TCP_CC_EVT_START_TX); + tcp_connection_tx_pacer_reset (tc, tc->cwnd, TRANSPORT_PACER_MIN_MSS); + } } #endif /* CLIB_MARCH_VARIANT */ @@ -1435,19 +1438,7 @@ tcp_prepare_retransmit_segment (tcp_worker_ctx_t * wrk, max_deq_bytes = clib_min (tc->snd_mss, max_deq_bytes); max_deq_bytes = clib_min (available_bytes, max_deq_bytes); - /* Start is beyond snd_congestion */ start = tc->snd_una + offset; - if (seq_geq (start, tc->snd_congestion)) - return 0; - - /* Don't overshoot snd_congestion */ - if (seq_gt (start + max_deq_bytes, tc->snd_congestion)) - { - max_deq_bytes = tc->snd_congestion - start; - if (max_deq_bytes == 0) - return 0; - } - n_bytes = tcp_prepare_segment (wrk, tc, offset, max_deq_bytes, b); if (!n_bytes) return 0; @@ -1903,17 +1894,28 @@ static int tcp_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, u32 burst_size) { + u8 snd_limited = 0, can_rescue = 0, reset_pacer = 0; u32 n_written = 0, offset, max_bytes, n_segs = 0; + u32 bi, max_deq, burst_bytes, sent_bytes; sack_scoreboard_hole_t *hole; vlib_main_t *vm = wrk->vm; vlib_buffer_t *b = 0; sack_scoreboard_t *sb; - u32 bi, max_deq; int snd_space; - u8 snd_limited = 0, can_rescue = 0; + u64 time_now; ASSERT (tcp_in_cong_recovery (tc)); + time_now = wrk->vm->clib_time.last_cpu_time; + burst_bytes = transport_connection_tx_pacer_burst (&tc->connection, + time_now); + burst_size = clib_min (burst_size, burst_bytes / tc->snd_mss); + if (!burst_size) + { + tcp_program_retransmit (tc); + return 0; + } + if (tcp_in_recovery (tc)) snd_space = tcp_available_cc_snd_space (tc); else @@ -1921,13 +1923,12 @@ tcp_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, if (snd_space < tc->snd_mss) { - /* We're cc constrained so don't accumulate tokens */ - transport_connection_tx_pacer_reset_bucket (&tc->connection, - vm-> - clib_time.last_cpu_time); - return 0; + reset_pacer = burst_bytes > tc->snd_mss; + goto done; } + reset_pacer = snd_space < burst_bytes; + sb = &tc->sack_sb; /* Check if snd_una is a lost retransmit */ @@ -1967,9 +1968,12 @@ tcp_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, /* We are out of lost holes to retransmit so send some new data. */ if (max_deq > tc->snd_mss) { - u32 n_segs_new, av_window; - av_window = tc->snd_wnd - (tc->snd_nxt - tc->snd_una); - snd_space = clib_min (snd_space, av_window); + u32 n_segs_new; + int av_wnd; + + av_wnd = (int) tc->snd_wnd - (tc->snd_nxt - tc->snd_una); + av_wnd = clib_max (av_wnd, 0); + snd_space = clib_min (snd_space, av_wnd); snd_space = clib_min (max_deq, snd_space); burst_size = clib_min (burst_size - n_segs, snd_space / tc->snd_mss); @@ -2034,6 +2038,19 @@ tcp_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, done: + if (reset_pacer) + { + transport_connection_tx_pacer_reset_bucket (&tc->connection, + vm->clib_time. + last_cpu_time); + } + else + { + sent_bytes = clib_min (n_segs * tc->snd_mss, burst_bytes); + transport_connection_tx_pacer_update_bytes (&tc->connection, + sent_bytes); + } + return n_segs; } @@ -2045,14 +2062,28 @@ tcp_retransmit_no_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, u32 burst_size) { u32 n_written = 0, offset = 0, bi, max_deq, n_segs_now; + u32 burst_bytes, sent_bytes; vlib_main_t *vm = wrk->vm; int snd_space, n_segs = 0; + u8 cc_limited = 0; vlib_buffer_t *b; + u64 time_now; ASSERT (tcp_in_fastrecovery (tc)); TCP_EVT (TCP_EVT_CC_EVT, tc, 0); + time_now = wrk->vm->clib_time.last_cpu_time; + burst_bytes = transport_connection_tx_pacer_burst (&tc->connection, + time_now); + burst_size = clib_min (burst_size, burst_bytes / tc->snd_mss); + if (!burst_size) + { + tcp_program_retransmit (tc); + return 0; + } + snd_space = tcp_available_cc_snd_space (tc); + cc_limited = snd_space < burst_bytes; if (!tcp_fastrecovery_first (tc)) goto send_unsent; @@ -2098,19 +2129,12 @@ send_unsent: done: tcp_fastrecovery_first_off (tc); - return n_segs; -} -/** - * Do fast retransmit - */ -static int -tcp_retransmit (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, u32 burst_size) -{ - if (tcp_opts_sack_permitted (&tc->rcv_opts)) - return tcp_retransmit_sack (wrk, tc, burst_size); - else - return tcp_retransmit_no_sack (wrk, tc, burst_size); + sent_bytes = clib_min (n_segs * tc->snd_mss, burst_bytes); + sent_bytes = cc_limited ? burst_bytes : sent_bytes; + transport_connection_tx_pacer_update_bytes (&tc->connection, sent_bytes); + + return n_segs; } static int @@ -2164,23 +2188,16 @@ tcp_send_acks (tcp_connection_t * tc, u32 max_burst_size) static int tcp_do_retransmit (tcp_connection_t * tc, u32 max_burst_size) { - u32 n_segs = 0, burst_size, sent_bytes, burst_bytes; tcp_worker_ctx_t *wrk; + u32 n_segs; wrk = tcp_get_worker (tc->c_thread_index); - burst_bytes = transport_connection_tx_pacer_burst (&tc->connection, - wrk->vm-> - clib_time.last_cpu_time); - burst_size = clib_min (max_burst_size, burst_bytes / tc->snd_mss); - if (!burst_size) - { - tcp_program_retransmit (tc); - return 0; - } - n_segs = tcp_retransmit (wrk, tc, burst_size); - sent_bytes = clib_min (n_segs * tc->snd_mss, burst_bytes); - transport_connection_tx_pacer_update_bytes (&tc->connection, sent_bytes); + if (tcp_opts_sack_permitted (&tc->rcv_opts)) + n_segs = tcp_retransmit_sack (wrk, tc, max_burst_size); + else + n_segs = tcp_retransmit_no_sack (wrk, tc, max_burst_size); + return n_segs; } -- cgit 1.2.3-korg