X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Ftcp%2Ftcp_output.c;h=bde06da87ed5e6c174ae008f37f0933485fa2716;hb=ea72764204dac0a1ab6412bc27b758faead2ca10;hp=91021e89d8535dfba83d954838ab26b85031cffb;hpb=7a3a8664bbc9e295d6382949d2d0bcd1998a05f1;p=vpp.git

diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 91021e89d85..bde06da87ed 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -14,7 +14,10 @@
  */
 
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 #include <math.h>
+#include <vnet/ip/ip4_inlines.h>
+#include <vnet/ip/ip6_inlines.h>
 
 typedef enum _tcp_output_next
 {
@@ -115,17 +118,10 @@ tcp_update_rcv_wnd (tcp_connection_t * tc)
   u32 available_space, wnd;
   i32 observed_wnd;
 
-  ASSERT (tc->rcv_opts.mss < transport_rx_fifo_size (&tc->connection));
-
   /*
    * Figure out how much space we have available
    */
   available_space = transport_max_rx_enqueue (&tc->connection);
-  if (PREDICT_FALSE (available_space < tc->rcv_opts.mss))
-    {
-      tc->rcv_wnd = 0;
-      return;
-    }
 
   /*
    * Use the above and what we know about what we've previously advertised
@@ -133,24 +129,22 @@ tcp_update_rcv_wnd (tcp_connection_t * tc)
    */
   observed_wnd = (i32) tc->rcv_wnd - (tc->rcv_nxt - tc->rcv_las);
 
-  /* Bad. Thou shalt not shrink */
+  /* Check if we are about to retract the window. Do the comparison before
+   * rounding to avoid errors. Per RFC7323 sec. 2.4 we could remove this */
   if (PREDICT_FALSE ((i32) available_space < observed_wnd))
     {
-      wnd = clib_max (observed_wnd, 0);
+      wnd = round_down_pow2 (clib_max (observed_wnd, 0), 1 << tc->rcv_wscale);
       TCP_EVT (TCP_EVT_RCV_WND_SHRUNK, tc, observed_wnd, available_space);
     }
   else
     {
-      wnd = available_space;
+      /* Make sure we have a multiple of 1 << rcv_wscale. We round down to
+       * avoid advertising a window larger than what can be buffered */
+      wnd = round_down_pow2 (available_space, 1 << tc->rcv_wscale);
     }
 
-  /* Make sure we have a multiple of rcv_wscale */
-  if (wnd && tc->rcv_wscale)
-    {
-      wnd &= ~((1 << tc->rcv_wscale) - 1);
-      if (wnd == 0)
-	wnd = 1 << tc->rcv_wscale;
-    }
+  if (PREDICT_FALSE (wnd < tc->rcv_opts.mss))
+    wnd = 0;
 
   tc->rcv_wnd = clib_min (wnd, TCP_WND_MAX << tc->rcv_wscale);
 }
@@ -168,90 +162,6 @@ tcp_window_to_advertise (tcp_connection_t * tc, tcp_state_t state)
   return tc->rcv_wnd >> tc->rcv_wscale;
 }
 
-/**
- * Write TCP options to segment.
- */
-static u32
-tcp_options_write (u8 * data, tcp_options_t * opts)
-{
-  u32 opts_len = 0;
-  u32 buf, seq_len = 4;
-
-  if (tcp_opts_mss (opts))
-    {
-      *data++ = TCP_OPTION_MSS;
-      *data++ = TCP_OPTION_LEN_MSS;
-      buf = clib_host_to_net_u16 (opts->mss);
-      clib_memcpy_fast (data, &buf, sizeof (opts->mss));
-      data += sizeof (opts->mss);
-      opts_len += TCP_OPTION_LEN_MSS;
-    }
-
-  if (tcp_opts_wscale (opts))
-    {
-      *data++ = TCP_OPTION_WINDOW_SCALE;
-      *data++ = TCP_OPTION_LEN_WINDOW_SCALE;
-      *data++ = opts->wscale;
-      opts_len += TCP_OPTION_LEN_WINDOW_SCALE;
-    }
-
-  if (tcp_opts_sack_permitted (opts))
-    {
-      *data++ = TCP_OPTION_SACK_PERMITTED;
-      *data++ = TCP_OPTION_LEN_SACK_PERMITTED;
-      opts_len += TCP_OPTION_LEN_SACK_PERMITTED;
-    }
-
-  if (tcp_opts_tstamp (opts))
-    {
-      *data++ = TCP_OPTION_TIMESTAMP;
-      *data++ = TCP_OPTION_LEN_TIMESTAMP;
-      buf = clib_host_to_net_u32 (opts->tsval);
-      clib_memcpy_fast (data, &buf, sizeof (opts->tsval));
-      data += sizeof (opts->tsval);
-      buf = clib_host_to_net_u32 (opts->tsecr);
-      clib_memcpy_fast (data, &buf, sizeof (opts->tsecr));
-      data += sizeof (opts->tsecr);
-      opts_len += TCP_OPTION_LEN_TIMESTAMP;
-    }
-
-  if (tcp_opts_sack (opts))
-    {
-      int i;
-
-      if (opts->n_sack_blocks != 0)
-	{
-	  *data++ = TCP_OPTION_SACK_BLOCK;
-	  *data++ = 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
-	  for (i = 0; i < opts->n_sack_blocks; i++)
-	    {
-	      buf = clib_host_to_net_u32 (opts->sacks[i].start);
-	      clib_memcpy_fast (data, &buf, seq_len);
-	      data += seq_len;
-	      buf = clib_host_to_net_u32 (opts->sacks[i].end);
-	      clib_memcpy_fast (data, &buf, seq_len);
-	      data += seq_len;
-	    }
-	  opts_len += 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
-	}
-    }
-
-  /* Terminate TCP options */
-  if (opts_len % 4)
-    {
-      *data++ = TCP_OPTION_EOL;
-      opts_len += TCP_OPTION_LEN_EOL;
-    }
-
-  /* Pad with zeroes to a u32 boundary */
-  while (opts_len % 4)
-    {
-      *data++ = TCP_OPTION_NOOP;
-      opts_len += TCP_OPTION_LEN_NOOP;
-    }
-  return opts_len;
-}
-
 static int
 tcp_make_syn_options (tcp_connection_t * tc, tcp_options_t * opts)
 {
@@ -266,7 +176,7 @@ tcp_make_syn_options (tcp_connection_t * tc, tcp_options_t * opts)
   len += TCP_OPTION_LEN_WINDOW_SCALE;
 
   opts->flags |= TCP_OPTS_FLAG_TSTAMP;
-  opts->tsval = tcp_time_now ();
+  opts->tsval = tcp_time_tstamp (tc->c_thread_index);
   opts->tsecr = 0;
   len += TCP_OPTION_LEN_TIMESTAMP;
 
@@ -300,7 +210,7 @@ tcp_make_synack_options (tcp_connection_t * tc, tcp_options_t * opts)
   if (tcp_opts_tstamp (&tc->rcv_opts))
     {
       opts->flags |= TCP_OPTS_FLAG_TSTAMP;
-      opts->tsval = tcp_time_now ();
+      opts->tsval = tcp_time_tstamp (tc->c_thread_index);
       opts->tsecr = tc->tsval_recent;
       len += TCP_OPTION_LEN_TIMESTAMP;
     }
@@ -413,6 +323,13 @@ tcp_update_burst_snd_vars (tcp_connection_t * tc)
       tcp_cc_event (tc, TCP_CC_EVT_START_TX);
       tcp_connection_tx_pacer_reset (tc, tc->cwnd, TRANSPORT_PACER_MIN_BURST);
     }
+
+  if (tc->flags & TCP_CONN_PSH_PENDING)
+    {
+      u32 max_deq = transport_max_tx_dequeue (&tc->connection);
+      /* Last byte marked for push */
+      tc->psh_seq = tc->snd_una + max_deq - 1;
+    }
 }
 
 #endif /* CLIB_MARCH_VARIANT */
@@ -428,7 +345,7 @@ tcp_reuse_buffer (vlib_main_t * vm, vlib_buffer_t * b)
   b->current_length = 0;
   b->total_length_not_including_first_buffer = 0;
   vnet_buffer (b)->tcp.flags = 0;
-
+  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   /* Leave enough space for headers */
   return vlib_buffer_make_headroom (b, TRANSPORT_MAX_HDRS_LEN);
 }
@@ -442,7 +359,6 @@ tcp_init_buffer (vlib_main_t * vm, vlib_buffer_t * b)
   b->total_length_not_including_first_buffer = 0;
   b->current_data = 0;
   vnet_buffer (b)->tcp.flags = 0;
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   /* Leave enough space for headers */
   return vlib_buffer_make_headroom (b, TRANSPORT_MAX_HDRS_LEN);
 }
@@ -513,7 +429,7 @@ tcp_compute_checksum (tcp_connection_t * tc, vlib_buffer_t * b)
     }
   else
     {
-      b->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
+      vnet_buffer_offload_flags_set (b, VNET_BUFFER_OFFLOAD_F_TCP_CKSUM);
     }
   return checksum;
 }
@@ -546,7 +462,10 @@ tcp_make_ack_i (tcp_connection_t * tc, vlib_buffer_t * b, tcp_state_t state,
   vnet_buffer (b)->tcp.connection_index = tc->c_c_index;
 
   if (wnd == 0)
-    tcp_zero_rwnd_sent_on (tc);
+    {
+      transport_rx_fifo_req_deq_ntf (&tc->connection);
+      tcp_zero_rwnd_sent_on (tc);
+    }
   else
     tcp_zero_rwnd_sent_off (tc);
 }
@@ -565,7 +484,7 @@ tcp_make_ack (tcp_connection_t * tc, vlib_buffer_t * b)
 /**
  * Convert buffer to FIN-ACK
  */
-void
+static void
 tcp_make_fin (tcp_connection_t * tc, vlib_buffer_t * b)
 {
   tcp_make_ack_i (tc, b, TCP_STATE_ESTABLISHED, TCP_FLAG_FIN | TCP_FLAG_ACK);
@@ -600,7 +519,7 @@ tcp_make_syn (tcp_connection_t * tc, vlib_buffer_t * b)
 /**
  * Convert buffer to SYN-ACK
  */
-void
+static void
 tcp_make_synack (tcp_connection_t * tc, vlib_buffer_t * b)
 {
   tcp_options_t _snd_opts, *snd_opts = &_snd_opts;
@@ -622,13 +541,12 @@ tcp_make_synack (tcp_connection_t * tc, vlib_buffer_t * b)
   th->checksum = tcp_compute_checksum (tc, b);
 }
 
-always_inline void
-tcp_enqueue_to_ip_lookup_i (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
-			    u8 is_ip4, u32 fib_index, u8 flush)
+static void
+tcp_enqueue_to_ip_lookup (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
+			  u8 is_ip4, u32 fib_index)
 {
+  tcp_main_t *tm = &tcp_main;
   vlib_main_t *vm = wrk->vm;
-  u32 *to_next, next_index;
-  vlib_frame_t *f;
 
   b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
   b->error = 0;
@@ -636,55 +554,22 @@ tcp_enqueue_to_ip_lookup_i (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
   vnet_buffer (b)->sw_if_index[VLIB_TX] = fib_index;
   vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
 
-  /* Send to IP lookup */
-  next_index = is_ip4 ? ip4_lookup_node.index : ip6_lookup_node.index;
-  tcp_trajectory_add_start (b, 1);
+  session_add_pending_tx_buffer (vm->thread_index, bi,
+				 tm->ipl_next_node[!is_ip4]);
 
-  f = wrk->ip_lookup_tx_frames[!is_ip4];
-  if (!f)
-    {
-      f = vlib_get_frame_to_node (vm, next_index);
-      ASSERT (f);
-      wrk->ip_lookup_tx_frames[!is_ip4] = f;
-    }
-
-  to_next = vlib_frame_vector_args (f);
-  to_next[f->n_vectors] = bi;
-  f->n_vectors += 1;
-  if (flush || f->n_vectors == VLIB_FRAME_SIZE)
-    {
-      vlib_put_frame_to_node (vm, next_index, f);
-      wrk->ip_lookup_tx_frames[!is_ip4] = 0;
-    }
-}
-
-static void
-tcp_enqueue_to_ip_lookup_now (tcp_worker_ctx_t * wrk, vlib_buffer_t * b,
-			      u32 bi, u8 is_ip4, u32 fib_index)
-{
-  tcp_enqueue_to_ip_lookup_i (wrk, b, bi, is_ip4, fib_index, 1);
-}
-
-static void
-tcp_enqueue_to_ip_lookup (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
-			  u8 is_ip4, u32 fib_index)
-{
-  tcp_enqueue_to_ip_lookup_i (wrk, b, bi, is_ip4, fib_index, 0);
-  if (wrk->vm->thread_index == 0 && vlib_num_workers ())
-    session_flush_frames_main_thread (wrk->vm);
+  if (vm->thread_index == 0 && vlib_num_workers ())
+    session_queue_run_on_main_thread (wrk->vm);
 }
 
 static void
 tcp_enqueue_to_output (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
 		       u8 is_ip4)
 {
-  session_type_t st;
-
   b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
   b->error = 0;
 
-  st = session_type_from_proto_and_ip (TRANSPORT_PROTO_TCP, is_ip4);
-  session_add_pending_tx_buffer (st, wrk->vm->thread_index, bi);
+  session_add_pending_tx_buffer (wrk->vm->thread_index, bi,
+				 wrk->tco_next_node[!is_ip4]);
 }
 
 #endif /* CLIB_MARCH_VARIANT */
@@ -745,7 +630,6 @@ tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b, u8 is_ip4)
     }
 
   tcp_reuse_buffer (vm, b);
-  tcp_trajectory_add_start (b, 4);
   th = vlib_buffer_push_tcp_net_order (b, dst_port, src_port, seq, ack,
 				       sizeof (tcp_header_t), flags, 0);
 
@@ -788,7 +672,10 @@ tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt,
   fib_protocol_t fib_proto;
 
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
-    return;
+    {
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
+      return;
+    }
 
   b = vlib_get_buffer (vm, bi);
   sw_if_index = vnet_buffer (pkt)->sw_if_index[VLIB_RX];
@@ -848,7 +735,7 @@ tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt,
       ASSERT (!bogus);
     }
 
-  tcp_enqueue_to_ip_lookup_now (wrk, b, bi, is_ip4, fib_index);
+  tcp_enqueue_to_ip_lookup (wrk, b, bi, is_ip4, fib_index);
   TCP_EVT (TCP_EVT_RST_SENT, tc);
   vlib_node_increment_counter (vm, tcp_node_index (output, tc->c_is_ip4),
 			       TCP_ERROR_RST_SENT, 1);
@@ -869,13 +756,16 @@ tcp_send_reset (tcp_connection_t * tc)
   u8 flags;
 
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
-    return;
+    {
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
+      return;
+    }
   b = vlib_get_buffer (vm, bi);
   tcp_init_buffer (vm, b);
 
   tc->snd_opts_len = tcp_make_options (tc, &tc->snd_opts, tc->state);
   tcp_hdr_opts_len = tc->snd_opts_len + sizeof (tcp_header_t);
-  advertise_wnd = tcp_window_to_advertise (tc, TCP_STATE_ESTABLISHED);
+  advertise_wnd = tc->rcv_wnd >> tc->rcv_wscale;
   flags = TCP_FLAG_RST;
   th = vlib_buffer_push_tcp (b, tc->c_lcl_port, tc->c_rmt_port, tc->snd_nxt,
 			     tc->rcv_nxt, tcp_hdr_opts_len, flags,
@@ -925,12 +815,13 @@ tcp_send_syn (tcp_connection_t * tc)
    * Setup retransmit and establish timers before requesting buffer
    * such that we can return if we've ran out.
    */
-  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN,
+  tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT_SYN,
 		    tc->rto * TCP_TO_TIMER_TICK);
 
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
-      tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN, 1);
+      tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT_SYN, 1);
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
       return;
     }
 
@@ -956,11 +847,13 @@ tcp_send_synack (tcp_connection_t * tc)
   vlib_buffer_t *b;
   u32 bi;
 
-  tcp_retransmit_timer_force_update (tc);
+  ASSERT (tc->snd_una != tc->snd_nxt);
+  tcp_retransmit_timer_update (&wrk->timer_wheel, tc);
 
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
-      tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
+      tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT, 1);
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
       return;
     }
 
@@ -991,12 +884,13 @@ tcp_send_fin (tcp_connection_t * tc)
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
       /* Out of buffers so program fin retransmit ASAP */
-      tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
+      tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT, 1);
       if (fin_snt)
 	tc->snd_nxt += 1;
       else
 	/* Make sure retransmit retries a fin not data */
 	tc->flags |= TCP_CONN_FINSNT;
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
       return;
     }
 
@@ -1004,7 +898,6 @@ tcp_send_fin (tcp_connection_t * tc)
   if ((tc->flags & TCP_CONN_SNDACK) && !tc->pending_dupacks)
     tc->flags &= ~TCP_CONN_SNDACK;
 
-  tcp_retransmit_timer_force_update (tc);
   b = vlib_get_buffer (vm, bi);
   tcp_init_buffer (vm, b);
   tcp_make_fin (tc, b);
@@ -1012,11 +905,11 @@ tcp_send_fin (tcp_connection_t * tc)
   TCP_EVT (TCP_EVT_FIN_SENT, tc);
   /* Account for the FIN */
   tc->snd_nxt += 1;
+  tcp_retransmit_timer_update (&wrk->timer_wheel, tc);
   if (!fin_snt)
     {
       tc->flags |= TCP_CONN_FINSNT;
       tc->flags &= ~TCP_CONN_FINPNDG;
-      tc->snd_una_max = seq_max (tc->snd_una_max, tc->snd_nxt);
     }
 }
 
@@ -1108,8 +1001,7 @@ tcp_session_push_header (transport_connection_t * tconn, vlib_buffer_t * b)
   tcp_push_hdr_i (tc, b, tc->snd_nxt, /* compute opts */ 0, /* burst */ 1,
 		  /* update_snd_nxt */ 1);
 
-  tc->snd_una_max = seq_max (tc->snd_nxt, tc->snd_una_max);
-  tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
+  tcp_validate_txf_size (tc, tc->snd_nxt - tc->snd_una);
   /* If not tracking an ACK, start tracking */
   if (tc->rtt_ts == 0 && !tcp_in_cong_recovery (tc))
     {
@@ -1118,10 +1010,10 @@ tcp_session_push_header (transport_connection_t * tconn, vlib_buffer_t * b)
     }
   if (PREDICT_FALSE (!tcp_timer_is_active (tc, TCP_TIMER_RETRANSMIT)))
     {
-      tcp_retransmit_timer_set (tc);
+      tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+      tcp_retransmit_timer_set (&wrk->timer_wheel, tc);
       tc->rto_boff = 0;
     }
-  tcp_trajectory_add_start (b, 3);
   return 0;
 }
 
@@ -1136,6 +1028,7 @@ tcp_send_ack (tcp_connection_t * tc)
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
       tcp_update_rcv_wnd (tc);
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
       return;
     }
   b = vlib_get_buffer (vm, bi);
@@ -1176,17 +1069,6 @@ tcp_program_retransmit (tcp_connection_t * tc)
     }
 }
 
-/**
- * Delayed ack timer handler
- *
- * Sends delayed ACK when timer expires
- */
-void
-tcp_timer_delack_handler (tcp_connection_t * tc)
-{
-  tcp_send_ack (tc);
-}
-
 /**
  * Send window update ack
  *
@@ -1245,7 +1127,10 @@ tcp_prepare_segment (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
   if (PREDICT_TRUE (seg_size <= bytes_per_buffer))
     {
       if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
-	return 0;
+	{
+	  tcp_worker_stats_inc (wrk, no_buffer, 1);
+	  return 0;
+	}
       *b = vlib_get_buffer (vm, bi);
       data = tcp_init_buffer (vm, *b);
       n_bytes = session_tx_fifo_peek_bytes (&tc->connection, data, offset,
@@ -1272,6 +1157,7 @@ tcp_prepare_segment (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 	{
 	  if (n_bufs)
 	    vlib_buffer_free (vm, wrk->tx_buffers, n_bufs);
+	  tcp_worker_stats_inc (wrk, no_buffer, 1);
 	  return 0;
 	}
 
@@ -1369,7 +1255,7 @@ tcp_prepare_retransmit_segment (tcp_worker_ctx_t * wrk,
 
   tc->bytes_retrans += n_bytes;
   tc->segs_retrans += 1;
-  tcp_workerp_stats_inc (wrk, rxt_segs, 1);
+  tcp_worker_stats_inc (wrk, rxt_segs, 1);
   TCP_EVT (TCP_EVT_CC_RTX, tc, offset, n_bytes);
 
   return n_bytes;
@@ -1410,6 +1296,7 @@ tcp_cc_init_rxt_timeout (tcp_connection_t * tc)
   tc->rtt_ts = 0;
   tc->cwnd_acc_bytes = 0;
   tc->tr_occurences += 1;
+  tc->sack_sb.reorder = TCP_DUPACK_THRESHOLD;
   tcp_recovery_on (tc);
 }
 
@@ -1421,7 +1308,7 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
   vlib_buffer_t *b = 0;
   u32 bi, n_bytes;
 
-  tcp_workerp_stats_inc (wrk, tr_events, 1);
+  tcp_worker_stats_inc (wrk, tr_events, 1);
 
   /* Should be handled by a different handler */
   if (PREDICT_FALSE (tc->state == TCP_STATE_SYN_SENT))
@@ -1444,11 +1331,8 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
 	  return;
 	}
 
-      /* Shouldn't be here. This condition is tricky because it has to take
-       * into account boff > 0 due to persist timeout. */
-      if ((tc->rto_boff == 0 && tc->snd_una == tc->snd_nxt)
-	  || (tc->rto_boff > 0 && seq_geq (tc->snd_una, tc->snd_congestion)
-	      && !tcp_flight_size (tc)))
+      /* Shouldn't be here */
+      if (tc->snd_una == tc->snd_nxt)
 	{
 	  ASSERT (!tcp_in_recovery (tc));
 	  tc->rto_boff = 0;
@@ -1474,7 +1358,7 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
 	  session_transport_closed_notify (&tc->connection);
 	  tcp_connection_timers_reset (tc);
 	  tcp_program_cleanup (wrk, tc);
-	  tcp_workerp_stats_inc (wrk, tr_abort, 1);
+	  tcp_worker_stats_inc (wrk, tr_abort, 1);
 	  return;
 	}
 
@@ -1490,7 +1374,7 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
       n_bytes = tcp_prepare_retransmit_segment (wrk, tc, 0, n_bytes, &b);
       if (!n_bytes)
 	{
-	  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
+	  tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT, 1);
 	  return;
 	}
 
@@ -1498,7 +1382,7 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
       tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
 
       tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
-      tcp_retransmit_timer_force_update (tc);
+      tcp_retransmit_timer_update (&wrk->timer_wheel, tc);
 
       tc->rto_boff += 1;
       if (tc->rto_boff == 1)
@@ -1526,13 +1410,14 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
 	  tcp_connection_set_state (tc, TCP_STATE_CLOSED);
 	  tcp_connection_timers_reset (tc);
 	  tcp_program_cleanup (wrk, tc);
-	  tcp_workerp_stats_inc (wrk, tr_abort, 1);
+	  tcp_worker_stats_inc (wrk, tr_abort, 1);
 	  return;
 	}
 
       if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
 	{
-	  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
+	  tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT, 1);
+	  tcp_worker_stats_inc (wrk, no_buffer, 1);
 	  return;
 	}
 
@@ -1540,7 +1425,8 @@ tcp_timer_retransmit_handler (tcp_connection_t * tc)
       if (tc->rto_boff > TCP_RTO_SYN_RETRIES)
 	tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
 
-      tcp_retransmit_timer_force_update (tc);
+      ASSERT (tc->snd_una != tc->snd_nxt);
+      tcp_retransmit_timer_update (&wrk->timer_wheel, tc);
 
       b = vlib_get_buffer (vm, bi);
       tcp_init_buffer (vm, b);
@@ -1588,14 +1474,15 @@ tcp_timer_retransmit_syn_handler (tcp_connection_t * tc)
   /* Active open establish timeout */
   if (tc->rto >= TCP_ESTABLISH_TIME >> 1)
     {
-      session_stream_connect_notify (&tc->connection, 1 /* fail */ );
+      session_stream_connect_notify (&tc->connection, SESSION_E_TIMEDOUT);
       tcp_connection_cleanup (tc);
       return;
     }
 
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
-      tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN, 1);
+      tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT_SYN, 1);
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
       return;
     }
 
@@ -1615,7 +1502,7 @@ tcp_timer_retransmit_syn_handler (tcp_connection_t * tc)
   tcp_push_ip_hdr (wrk, tc, b);
   tcp_enqueue_to_ip_lookup (wrk, b, bi, tc->c_is_ip4, tc->c_fib_index);
 
-  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN,
+  tcp_timer_update (&wrk->timer_wheel, tc, TCP_TIMER_RETRANSMIT_SYN,
 		    tc->rto * TCP_TO_TIMER_TICK);
 }
 
@@ -1637,7 +1524,7 @@ tcp_timer_persist_handler (tcp_connection_t * tc)
   /* Problem already solved or worse */
   if (tc->state == TCP_STATE_CLOSED || tc->snd_wnd > tc->snd_mss
       || (tc->flags & TCP_CONN_FINSNT))
-    return;
+    goto update_scheduler;
 
   available_bytes = transport_max_tx_dequeue (&tc->connection);
   offset = tc->snd_nxt - tc->snd_una;
@@ -1646,12 +1533,12 @@ tcp_timer_persist_handler (tcp_connection_t * tc)
    * next time */
   if (!available_bytes)
     {
-      tcp_persist_timer_set (tc);
+      tcp_persist_timer_set (&wrk->timer_wheel, tc);
       return;
     }
 
   if (available_bytes <= offset)
-    return;
+    goto update_scheduler;
 
   /* Increment RTO backoff */
   tc->rto_boff += 1;
@@ -1662,9 +1549,11 @@ tcp_timer_persist_handler (tcp_connection_t * tc)
    */
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
-      tcp_persist_timer_set (tc);
+      tcp_persist_timer_set (&wrk->timer_wheel, tc);
+      tcp_worker_stats_inc (wrk, no_buffer, 1);
       return;
     }
+
   b = vlib_get_buffer (vm, bi);
   data = tcp_init_buffer (vm, b);
 
@@ -1676,7 +1565,7 @@ tcp_timer_persist_handler (tcp_connection_t * tc)
 					max_snd_bytes);
   b->current_length = n_bytes;
   ASSERT (n_bytes != 0 && (tcp_timer_is_active (tc, TCP_TIMER_RETRANSMIT)
-			   || tc->snd_nxt == tc->snd_una_max
+			   || tc->snd_una == tc->snd_nxt
 			   || tc->rto_boff > 1));
 
   if (tc->cfg_flags & TCP_CFG_F_RATE_SAMPLE)
@@ -1687,12 +1576,18 @@ tcp_timer_persist_handler (tcp_connection_t * tc)
 
   tcp_push_hdr_i (tc, b, tc->snd_nxt, /* compute opts */ 0,
 		  /* burst */ 0, /* update_snd_nxt */ 1);
-  tc->snd_una_max = seq_max (tc->snd_nxt, tc->snd_una_max);
-  tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
+  tcp_validate_txf_size (tc, tc->snd_nxt - tc->snd_una);
   tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
 
   /* Just sent new data, enable retransmit */
-  tcp_retransmit_timer_update (tc);
+  tcp_retransmit_timer_update (&wrk->timer_wheel, tc);
+
+  return;
+
+update_scheduler:
+
+  if (tcp_is_descheduled (tc))
+    transport_connection_reschedule (&tc->connection);
 }
 
 /**
@@ -1747,7 +1642,6 @@ tcp_transmit_unsent (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 	tcp_bt_track_tx (tc, n_written);
 
       tc->snd_nxt += n_written;
-      tc->snd_una_max = seq_max (tc->snd_nxt, tc->snd_una_max);
     }
 
 done:
@@ -2064,6 +1958,7 @@ tcp_send_acks (tcp_connection_t * tc, u32 max_burst_size)
   if (!vec_len (tc->snd_sacks))
     {
       tcp_send_ack (tc);
+      tc->dupacks_out += 1;
       tc->pending_dupacks = 0;
       return 1;
     }
@@ -2117,7 +2012,7 @@ tcp_do_retransmit (tcp_connection_t * tc, u32 max_burst_size)
 }
 
 int
-tcp_session_custom_tx (void *conn, u32 max_burst_size)
+tcp_session_custom_tx (void *conn, transport_send_params_t * sp)
 {
   tcp_connection_t *tc = (tcp_connection_t *) conn;
   u32 n_segs = 0;
@@ -2125,8 +2020,7 @@ tcp_session_custom_tx (void *conn, u32 max_burst_size)
   if (tcp_in_cong_recovery (tc) && (tc->flags & TCP_CONN_RXT_PENDING))
     {
       tc->flags &= ~TCP_CONN_RXT_PENDING;
-      n_segs = tcp_do_retransmit (tc, max_burst_size);
-      max_burst_size -= n_segs;
+      n_segs = tcp_do_retransmit (tc, sp->max_burst_size);
     }
 
   if (!(tc->flags & TCP_CONN_SNDACK))
@@ -2138,13 +2032,13 @@ tcp_session_custom_tx (void *conn, u32 max_burst_size)
   if (n_segs && !tc->pending_dupacks)
     return n_segs;
 
-  if (!max_burst_size)
+  if (sp->max_burst_size <= n_segs)
     {
       tcp_program_ack (tc);
-      return max_burst_size;
+      return n_segs;
     }
 
-  n_segs += tcp_send_acks (tc, max_burst_size);
+  n_segs += tcp_send_acks (tc, sp->max_burst_size - n_segs);
 
   return n_segs;
 }
@@ -2279,9 +2173,6 @@ tcp_output_handle_packet (tcp_connection_t * tc0, vlib_buffer_t * b0,
 	}
     }
 
-  if (!TCP_ALWAYS_ACK)
-    tcp_timer_reset (tc0, TCP_TIMER_DELACK);
-
   tc0->segs_out += 1;
 }
 
@@ -2292,13 +2183,10 @@ tcp46_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
   u32 n_left_from, *from, thread_index = vm->thread_index;
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
   u16 nexts[VLIB_FRAME_SIZE], *next;
-  vlib_node_runtime_t *error_node;
-
-  error_node = vlib_node_get_runtime (vm, tcp_node_index (output, is_ip4));
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
-  tcp_set_time_now (tcp_get_worker (thread_index));
+  tcp_update_time_now (tcp_get_worker (thread_index));
 
   if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
     tcp46_output_trace_frame (vm, node, from, n_left_from);
@@ -2332,8 +2220,8 @@ tcp46_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  tcp_check_if_gso (tc0, b[0]);
 	  tcp_check_if_gso (tc1, b[1]);
 
-	  tcp_output_handle_packet (tc0, b[0], error_node, &next[0], is_ip4);
-	  tcp_output_handle_packet (tc1, b[1], error_node, &next[1], is_ip4);
+	  tcp_output_handle_packet (tc0, b[0], node, &next[0], is_ip4);
+	  tcp_output_handle_packet (tc1, b[1], node, &next[1], is_ip4);
 	}
       else
 	{
@@ -2341,24 +2229,22 @@ tcp46_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    {
 	      tcp_output_push_ip (vm, b[0], tc0, is_ip4);
 	      tcp_check_if_gso (tc0, b[0]);
-	      tcp_output_handle_packet (tc0, b[0], error_node, &next[0],
-					is_ip4);
+	      tcp_output_handle_packet (tc0, b[0], node, &next[0], is_ip4);
 	    }
 	  else
 	    {
-	      b[0]->error = error_node->errors[TCP_ERROR_INVALID_CONNECTION];
+	      b[0]->error = node->errors[TCP_ERROR_INVALID_CONNECTION];
 	      next[0] = TCP_OUTPUT_NEXT_DROP;
 	    }
 	  if (tc1 != 0)
 	    {
 	      tcp_output_push_ip (vm, b[1], tc1, is_ip4);
 	      tcp_check_if_gso (tc1, b[1]);
-	      tcp_output_handle_packet (tc1, b[1], error_node, &next[1],
-					is_ip4);
+	      tcp_output_handle_packet (tc1, b[1], node, &next[1], is_ip4);
 	    }
 	  else
 	    {
-	      b[1]->error = error_node->errors[TCP_ERROR_INVALID_CONNECTION];
+	      b[1]->error = node->errors[TCP_ERROR_INVALID_CONNECTION];
 	      next[1] = TCP_OUTPUT_NEXT_DROP;
 	    }
 	}
@@ -2384,11 +2270,11 @@ tcp46_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	{
 	  tcp_output_push_ip (vm, b[0], tc0, is_ip4);
 	  tcp_check_if_gso (tc0, b[0]);
-	  tcp_output_handle_packet (tc0, b[0], error_node, &next[0], is_ip4);
+	  tcp_output_handle_packet (tc0, b[0], node, &next[0], is_ip4);
 	}
       else
 	{
-	  b[0]->error = error_node->errors[TCP_ERROR_INVALID_CONNECTION];
+	  b[0]->error = node->errors[TCP_ERROR_INVALID_CONNECTION];
 	  next[0] = TCP_OUTPUT_NEXT_DROP;
 	}