session: basic support for interrupt mode
[vpp.git] / src / vnet / session / session_node.c
index d0936c7..d7adbb5 100644 (file)
 #include <vnet/session/application_local.h>
 #include <vnet/session/session_debug.h>
 #include <svm/queue.h>
+#include <sys/timerfd.h>
 
-static void session_mq_accepted_reply_handler (void *data);
+#define app_check_thread_and_barrier(_fn, _arg)                                \
+  if (!vlib_thread_is_main_w_barrier ())                               \
+    {                                                                  \
+     vlib_rpc_call_main_thread (_fn, (u8 *) _arg, sizeof(*_arg));      \
+      return;                                                          \
+   }
 
 static void
-accepted_notify_cb (void *data, u32 data_len)
+session_mq_listen_handler (void *data)
 {
-  session_mq_accepted_reply_handler (data);
+  session_listen_msg_t *mp = (session_listen_msg_t *) data;
+  vnet_listen_args_t _a, *a = &_a;
+  app_worker_t *app_wrk;
+  application_t *app;
+  int rv;
+
+  app_check_thread_and_barrier (session_mq_listen_handler, mp);
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  clib_memset (a, 0, sizeof (*a));
+  a->sep.is_ip4 = mp->is_ip4;
+  ip_copy (&a->sep.ip, &mp->ip, mp->is_ip4);
+  a->sep.port = mp->port;
+  a->sep.fib_index = mp->vrf;
+  a->sep.sw_if_index = ENDPOINT_INVALID_INDEX;
+  a->sep.transport_proto = mp->proto;
+  a->sep_ext.ckpair_index = mp->ckpair_index;
+  a->sep_ext.crypto_engine = mp->crypto_engine;
+  a->app_index = app->app_index;
+  a->wrk_map_index = mp->wrk_index;
+  a->sep_ext.transport_flags = mp->flags;
+
+  if ((rv = vnet_listen (a)))
+    clib_warning ("listen returned: %U", format_session_error, rv);
+
+  app_wrk = application_get_worker (app, mp->wrk_index);
+  mq_send_session_bound_cb (app_wrk->wrk_index, mp->context, a->handle, rv);
+  return;
+}
+
+static void
+session_mq_listen_uri_handler (void *data)
+{
+  session_listen_uri_msg_t *mp = (session_listen_uri_msg_t *) data;
+  vnet_listen_args_t _a, *a = &_a;
+  app_worker_t *app_wrk;
+  application_t *app;
+  int rv;
+
+  app_check_thread_and_barrier (session_mq_listen_uri_handler, mp);
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  clib_memset (a, 0, sizeof (*a));
+  a->uri = (char *) mp->uri;
+  a->app_index = app->app_index;
+  rv = vnet_bind_uri (a);
+
+  app_wrk = application_get_worker (app, 0);
+  mq_send_session_bound_cb (app_wrk->wrk_index, mp->context, a->handle, rv);
+}
+
+static void
+session_mq_connect_handler (void *data)
+{
+  session_connect_msg_t *mp = (session_connect_msg_t *) data;
+  vnet_connect_args_t _a, *a = &_a;
+  app_worker_t *app_wrk;
+  application_t *app;
+  int rv;
+
+  app_check_thread_and_barrier (session_mq_connect_handler, mp);
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  clib_memset (a, 0, sizeof (*a));
+  a->sep.is_ip4 = mp->is_ip4;
+  clib_memcpy_fast (&a->sep.ip, &mp->ip, sizeof (mp->ip));
+  a->sep.port = mp->port;
+  a->sep.transport_proto = mp->proto;
+  a->sep.peer.fib_index = mp->vrf;
+  clib_memcpy_fast (&a->sep.peer.ip, &mp->lcl_ip, sizeof (mp->lcl_ip));
+  if (mp->is_ip4)
+    {
+      ip46_address_mask_ip4 (&a->sep.ip);
+      ip46_address_mask_ip4 (&a->sep.peer.ip);
+    }
+  a->sep.peer.port = mp->lcl_port;
+  a->sep.peer.sw_if_index = ENDPOINT_INVALID_INDEX;
+  a->sep_ext.parent_handle = mp->parent_handle;
+  a->sep_ext.ckpair_index = mp->ckpair_index;
+  a->sep_ext.crypto_engine = mp->crypto_engine;
+  a->sep_ext.transport_flags = mp->flags;
+  if (mp->hostname_len)
+    {
+      vec_validate (a->sep_ext.hostname, mp->hostname_len - 1);
+      clib_memcpy_fast (a->sep_ext.hostname, mp->hostname, mp->hostname_len);
+    }
+  a->api_context = mp->context;
+  a->app_index = app->app_index;
+  a->wrk_map_index = mp->wrk_index;
+
+  if ((rv = vnet_connect (a)))
+    {
+      clib_warning ("connect returned: %U", format_session_error, rv);
+      app_wrk = application_get_worker (app, mp->wrk_index);
+      mq_send_session_connected_cb (app_wrk->wrk_index, mp->context, 0, rv);
+    }
+
+  vec_free (a->sep_ext.hostname);
+}
+
+static void
+session_mq_connect_uri_handler (void *data)
+{
+  session_connect_uri_msg_t *mp = (session_connect_uri_msg_t *) data;
+  vnet_connect_args_t _a, *a = &_a;
+  app_worker_t *app_wrk;
+  application_t *app;
+  int rv;
+
+  app_check_thread_and_barrier (session_mq_connect_uri_handler, mp);
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  clib_memset (a, 0, sizeof (*a));
+  a->uri = (char *) mp->uri;
+  a->api_context = mp->context;
+  a->app_index = app->app_index;
+  if ((rv = vnet_connect_uri (a)))
+    {
+      clib_warning ("connect_uri returned: %d", rv);
+      app_wrk = application_get_worker (app, 0 /* default wrk only */ );
+      mq_send_session_connected_cb (app_wrk->wrk_index, mp->context, 0, rv);
+    }
+}
+
+static void
+session_mq_disconnect_handler (void *data)
+{
+  session_disconnect_msg_t *mp = (session_disconnect_msg_t *) data;
+  vnet_disconnect_args_t _a, *a = &_a;
+  application_t *app;
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  a->app_index = app->app_index;
+  a->handle = mp->handle;
+  vnet_disconnect_session (a);
+}
+
+static void
+app_mq_detach_handler (void *data)
+{
+  session_app_detach_msg_t *mp = (session_app_detach_msg_t *) data;
+  vnet_app_detach_args_t _a, *a = &_a;
+  application_t *app;
+
+  app_check_thread_and_barrier (app_mq_detach_handler, mp);
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  a->app_index = app->app_index;
+  a->api_client_index = mp->client_index;
+  vnet_application_detach (a);
+}
+
+static void
+session_mq_unlisten_handler (void *data)
+{
+  session_unlisten_msg_t *mp = (session_unlisten_msg_t *) data;
+  vnet_unlisten_args_t _a, *a = &_a;
+  app_worker_t *app_wrk;
+  application_t *app;
+  int rv;
+
+  app_check_thread_and_barrier (session_mq_unlisten_handler, mp);
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  clib_memset (a, 0, sizeof (*a));
+  a->app_index = app->app_index;
+  a->handle = mp->handle;
+  a->wrk_map_index = mp->wrk_index;
+  if ((rv = vnet_unlisten (a)))
+    clib_warning ("unlisten returned: %d", rv);
+
+  app_wrk = application_get_worker (app, a->wrk_map_index);
+  if (!app_wrk)
+    return;
+
+  mq_send_unlisten_reply (app_wrk, mp->handle, mp->context, rv);
 }
 
 static void
@@ -56,8 +258,8 @@ session_mq_accepted_reply_handler (void *data)
   if (vlib_num_workers () && vlib_get_thread_index () != 0
       && session_thread_from_handle (mp->handle) == 0)
     {
-      vl_api_rpc_call_main_thread (accepted_notify_cb, data,
-                                  sizeof (session_accepted_reply_msg_t));
+      vlib_rpc_call_main_thread (session_mq_accepted_reply_handler,
+                                (u8 *) mp, sizeof (*mp));
       return;
     }
 
@@ -74,22 +276,22 @@ session_mq_accepted_reply_handler (void *data)
 
   if (!session_has_transport (s))
     {
+      s->session_state = SESSION_STATE_READY;
       if (ct_session_connect_notify (s))
        return;
-      s->session_state = SESSION_STATE_READY;
     }
   else
     {
       old_state = s->session_state;
       s->session_state = SESSION_STATE_READY;
-      if (!svm_fifo_is_empty (s->rx_fifo))
+
+      if (!svm_fifo_is_empty_prod (s->rx_fifo))
        app_worker_lock_and_send_event (app_wrk, s, SESSION_IO_EVT_RX);
 
       /* Closed while waiting for app to reply. Resend disconnect */
       if (old_state >= SESSION_STATE_TRANSPORT_CLOSING)
        {
-         application_t *app = application_get (app_wrk->app_index);
-         app->cb_fns.session_disconnect_callback (s);
+         app_worker_close_notify (app_wrk, s);
          s->session_state = old_state;
          return;
        }
@@ -114,14 +316,14 @@ session_mq_reset_reply_handler (void *data)
   session_parse_handle (mp->handle, &index, &thread_index);
   s = session_get_if_valid (index, thread_index);
 
-  /* Session was already closed or already cleaned up */
-  if (!s || s->session_state != SESSION_STATE_TRANSPORT_CLOSING)
+  /* No session or not the right session */
+  if (!s || s->session_state < SESSION_STATE_TRANSPORT_CLOSING)
     return;
 
   app_wrk = app_worker_get (s->app_wrk_index);
   if (!app_wrk || app_wrk->app_index != app->app_index)
     {
-      clib_warning ("App % does not own handle 0x%lx!", app->app_index,
+      clib_warning ("App %u does not own handle 0x%lx!", app->app_index,
                    mp->handle);
       return;
     }
@@ -175,7 +377,6 @@ session_mq_disconnected_handler (void *data)
   svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
                                       SESSION_MQ_CTRL_EVT_RING,
                                       SVM_Q_WAIT, msg);
-  svm_msg_q_unlock (app_wrk->event_queue);
   evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
   clib_memset (evt, 0, sizeof (*evt));
   evt->event_type = SESSION_CTRL_EVT_DISCONNECTED_REPLY;
@@ -183,7 +384,7 @@ session_mq_disconnected_handler (void *data)
   rmp->handle = mp->handle;
   rmp->context = mp->context;
   rmp->retval = rv;
-  svm_msg_q_add (app_wrk->event_queue, msg, SVM_Q_WAIT);
+  svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
 }
 
 static void
@@ -250,13 +451,12 @@ session_mq_worker_update_handler (void *data)
       svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
                                           SESSION_MQ_CTRL_EVT_RING,
                                           SVM_Q_WAIT, msg);
-      svm_msg_q_unlock (app_wrk->event_queue);
       evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
       clib_memset (evt, 0, sizeof (*evt));
       evt->event_type = SESSION_CTRL_EVT_REQ_WORKER_UPDATE;
       wump = (session_req_worker_update_msg_t *) evt->data;
       wump->session_handle = mp->handle;
-      svm_msg_q_add (app_wrk->event_queue, msg, SVM_Q_WAIT);
+      svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
       return;
     }
 
@@ -268,16 +468,17 @@ session_mq_worker_update_handler (void *data)
   svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
                                       SESSION_MQ_CTRL_EVT_RING,
                                       SVM_Q_WAIT, msg);
-  svm_msg_q_unlock (app_wrk->event_queue);
   evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
   clib_memset (evt, 0, sizeof (*evt));
   evt->event_type = SESSION_CTRL_EVT_WORKER_UPDATE_REPLY;
   rmp = (session_worker_update_reply_msg_t *) evt->data;
   rmp->handle = mp->handle;
-  rmp->rx_fifo = pointer_to_uword (s->rx_fifo);
-  rmp->tx_fifo = pointer_to_uword (s->tx_fifo);
+  if (s->rx_fifo)
+    rmp->rx_fifo = fifo_segment_fifo_offset (s->rx_fifo);
+  if (s->tx_fifo)
+    rmp->tx_fifo = fifo_segment_fifo_offset (s->tx_fifo);
   rmp->segment_handle = session_segment_handle (s);
-  svm_msg_q_add (app_wrk->event_queue, msg, SVM_Q_WAIT);
+  svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
 
   /*
    * Retransmit messages that may have been lost
@@ -289,7 +490,34 @@ session_mq_worker_update_handler (void *data)
     app_worker_lock_and_send_event (app_wrk, s, SESSION_IO_EVT_RX);
 
   if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSING)
-    app->cb_fns.session_disconnect_callback (s);
+    app_worker_close_notify (app_wrk, s);
+}
+
+static void
+session_mq_app_wrk_rpc_handler (void *data)
+{
+  session_app_wrk_rpc_msg_t *mp = (session_app_wrk_rpc_msg_t *) data;
+  svm_msg_q_msg_t _msg, *msg = &_msg;
+  session_app_wrk_rpc_msg_t *rmp;
+  app_worker_t *app_wrk;
+  session_event_t *evt;
+  application_t *app;
+
+  app = application_lookup (mp->client_index);
+  if (!app)
+    return;
+
+  app_wrk = application_get_worker (app, mp->wrk_index);
+
+  svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
+                                      SESSION_MQ_CTRL_EVT_RING, SVM_Q_WAIT,
+                                      msg);
+  evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
+  clib_memset (evt, 0, sizeof (*evt));
+  evt->event_type = SESSION_CTRL_EVT_APP_WRK_RPC;
+  rmp = (session_app_wrk_rpc_msg_t *) evt->data;
+  clib_memcpy (rmp->data, mp->data, sizeof (mp->data));
+  svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
 }
 
 vlib_node_registration_t session_queue_node;
@@ -308,7 +536,7 @@ format_session_queue_trace (u8 * s, va_list * args)
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   session_queue_trace_t *t = va_arg (*args, session_queue_trace_t *);
 
-  s = format (s, "SESSION_QUEUE: session index %d, server thread index %d",
+  s = format (s, "session index %d thread index %d",
              t->session_index, t->server_thread_index);
   return s;
 }
@@ -344,19 +572,23 @@ session_tx_trace_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
                        u32 next_index, u32 * to_next, u16 n_segs,
                        session_t * s, u32 n_trace)
 {
-  session_queue_trace_t *t;
-  vlib_buffer_t *b;
-  int i;
-
-  for (i = 0; i < clib_min (n_trace, n_segs); i++)
+  while (n_trace && n_segs)
     {
-      b = vlib_get_buffer (vm, to_next[i - n_segs]);
-      vlib_trace_buffer (vm, node, next_index, b, 1 /* follow_chain */ );
-      t = vlib_add_trace (vm, node, b, sizeof (*t));
-      t->session_index = s->session_index;
-      t->server_thread_index = s->thread_index;
+      vlib_buffer_t *b = vlib_get_buffer (vm, to_next[0]);
+      if (PREDICT_TRUE
+         (vlib_trace_buffer
+          (vm, node, next_index, b, 1 /* follow_chain */ )))
+       {
+         session_queue_trace_t *t =
+           vlib_add_trace (vm, node, b, sizeof (*t));
+         t->session_index = s->session_index;
+         t->server_thread_index = s->thread_index;
+         n_trace--;
+       }
+      to_next++;
+      n_segs--;
     }
-  vlib_set_trace_count (vm, node, n_trace - i);
+  vlib_set_trace_count (vm, node, n_trace);
 }
 
 always_inline void
@@ -374,7 +606,7 @@ session_tx_fifo_chain_tail (vlib_main_t * vm, session_tx_context_t * ctx,
   b->total_length_not_including_first_buffer = 0;
 
   chain_b = b;
-  left_from_seg = clib_min (ctx->snd_mss - b->current_length,
+  left_from_seg = clib_min (ctx->sp.snd_mss - b->current_length,
                            ctx->left_to_snd);
   to_deq = left_from_seg;
   for (j = 1; j < ctx->n_bufs_per_seg; j++)
@@ -390,32 +622,41 @@ session_tx_fifo_chain_tail (vlib_main_t * vm, session_tx_context_t * ctx,
       if (peek_data)
        {
          n_bytes_read = svm_fifo_peek (ctx->s->tx_fifo,
-                                       ctx->tx_offset, len_to_deq, data);
-         ctx->tx_offset += n_bytes_read;
+                                       ctx->sp.tx_offset, len_to_deq, data);
+         ctx->sp.tx_offset += n_bytes_read;
        }
       else
        {
-         if (ctx->transport_vft->tx_type == TRANSPORT_TX_DGRAM)
+         if (ctx->transport_vft->transport_options.tx_type ==
+             TRANSPORT_TX_DGRAM)
            {
              svm_fifo_t *f = ctx->s->tx_fifo;
              session_dgram_hdr_t *hdr = &ctx->hdr;
              u16 deq_now;
+             u32 offset;
+
              deq_now = clib_min (hdr->data_length - hdr->data_offset,
                                  len_to_deq);
-             n_bytes_read = svm_fifo_peek (f, hdr->data_offset, deq_now,
-                                           data);
+             offset = hdr->data_offset + SESSION_CONN_HDR_LEN;
+             n_bytes_read = svm_fifo_peek (f, offset, deq_now, data);
              ASSERT (n_bytes_read > 0);
 
              hdr->data_offset += n_bytes_read;
              if (hdr->data_offset == hdr->data_length)
                {
-                 u32 offset = hdr->data_length + SESSION_CONN_HDR_LEN;
+                 offset = hdr->data_length + SESSION_CONN_HDR_LEN;
                  svm_fifo_dequeue_drop (f, offset);
+                 if (ctx->left_to_snd > n_bytes_read)
+                   svm_fifo_peek (ctx->s->tx_fifo, 0, sizeof (ctx->hdr),
+                                  (u8 *) & ctx->hdr);
                }
+             else if (ctx->left_to_snd == n_bytes_read)
+               svm_fifo_overwrite_head (ctx->s->tx_fifo, (u8 *) & ctx->hdr,
+                                        sizeof (session_dgram_pre_hdr_t));
            }
          else
-           n_bytes_read = svm_fifo_dequeue_nowait (ctx->s->tx_fifo,
-                                                   len_to_deq, data);
+           n_bytes_read = svm_fifo_dequeue (ctx->s->tx_fifo,
+                                            len_to_deq, data);
        }
       ASSERT (n_bytes_read == len_to_deq);
       chain_b->current_length = n_bytes_read;
@@ -457,16 +698,16 @@ session_tx_fill_buffer (vlib_main_t * vm, session_tx_context_t * ctx,
 
   if (peek_data)
     {
-      n_bytes_read = svm_fifo_peek (ctx->s->tx_fifo, ctx->tx_offset,
+      n_bytes_read = svm_fifo_peek (ctx->s->tx_fifo, ctx->sp.tx_offset,
                                    len_to_deq, data0);
       ASSERT (n_bytes_read > 0);
       /* Keep track of progress locally, transport is also supposed to
        * increment it independently when pushing the header */
-      ctx->tx_offset += n_bytes_read;
+      ctx->sp.tx_offset += n_bytes_read;
     }
   else
     {
-      if (ctx->transport_vft->tx_type == TRANSPORT_TX_DGRAM)
+      if (ctx->transport_vft->transport_options.tx_type == TRANSPORT_TX_DGRAM)
        {
          session_dgram_hdr_t *hdr = &ctx->hdr;
          svm_fifo_t *f = ctx->s->tx_fifo;
@@ -490,12 +731,18 @@ session_tx_fill_buffer (vlib_main_t * vm, session_tx_context_t * ctx,
            {
              offset = hdr->data_length + SESSION_CONN_HDR_LEN;
              svm_fifo_dequeue_drop (f, offset);
+             if (ctx->left_to_snd > n_bytes_read)
+               svm_fifo_peek (ctx->s->tx_fifo, 0, sizeof (ctx->hdr),
+                              (u8 *) & ctx->hdr);
            }
+         else if (ctx->left_to_snd == n_bytes_read)
+           svm_fifo_overwrite_head (ctx->s->tx_fifo, (u8 *) & ctx->hdr,
+                                    sizeof (session_dgram_pre_hdr_t));
        }
       else
        {
-         n_bytes_read = svm_fifo_dequeue_nowait (ctx->s->tx_fifo,
-                                                 len_to_deq, data0);
+         n_bytes_read = svm_fifo_dequeue (ctx->s->tx_fifo,
+                                          len_to_deq, data0);
          ASSERT (n_bytes_read > 0);
        }
     }
@@ -507,15 +754,6 @@ session_tx_fill_buffer (vlib_main_t * vm, session_tx_context_t * ctx,
    */
   if (PREDICT_FALSE (ctx->n_bufs_per_seg > 1 && ctx->left_to_snd))
     session_tx_fifo_chain_tail (vm, ctx, b, n_bufs, peek_data);
-
-  /* *INDENT-OFF* */
-  SESSION_EVT_DBG(SESSION_EVT_DEQ, ctx->s, ({
-       ed->data[0] = SESSION_IO_EVT_TX;
-       ed->data[1] = ctx->max_dequeue;
-       ed->data[2] = len_to_deq;
-       ed->data[3] = ctx->left_to_snd;
-  }));
-  /* *INDENT-ON* */
 }
 
 always_inline u8
@@ -523,12 +761,21 @@ session_tx_not_ready (session_t * s, u8 peek_data)
 {
   if (peek_data)
     {
+      if (PREDICT_TRUE (s->session_state == SESSION_STATE_READY))
+       return 0;
       /* Can retransmit for closed sessions but can't send new data if
        * session is not ready or closed */
-      if (s->session_state < SESSION_STATE_READY)
+      else if (s->session_state < SESSION_STATE_READY)
        return 1;
-      if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED)
-       return 2;
+      else if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED)
+       {
+         /* Allow closed transports to still send custom packets.
+          * For instance, tcp may want to send acks in time-wait. */
+         if (s->session_state != SESSION_STATE_TRANSPORT_DELETED
+             && (s->flags & SESSION_F_CUSTOM_TX))
+           return 0;
+         return 2;
+       }
     }
   return 0;
 }
@@ -558,78 +805,144 @@ session_tx_set_dequeue_params (vlib_main_t * vm, session_tx_context_t * ctx,
                               u32 max_segs, u8 peek_data)
 {
   u32 n_bytes_per_buf, n_bytes_per_seg;
-  ctx->max_dequeue = svm_fifo_max_dequeue (ctx->s->tx_fifo);
+
+  n_bytes_per_buf = vlib_buffer_get_default_data_size (vm);
+  ctx->max_dequeue = svm_fifo_max_dequeue_cons (ctx->s->tx_fifo);
+
   if (peek_data)
     {
       /* Offset in rx fifo from where to peek data */
-      ctx->tx_offset = ctx->transport_vft->tx_fifo_offset (ctx->tc);
-      if (PREDICT_FALSE (ctx->tx_offset >= ctx->max_dequeue))
+      if (PREDICT_FALSE (ctx->sp.tx_offset >= ctx->max_dequeue))
        {
          ctx->max_len_to_snd = 0;
          return;
        }
-      ctx->max_dequeue -= ctx->tx_offset;
+      ctx->max_dequeue -= ctx->sp.tx_offset;
     }
   else
     {
-      if (ctx->transport_vft->tx_type == TRANSPORT_TX_DGRAM)
+      if (ctx->transport_vft->transport_options.tx_type == TRANSPORT_TX_DGRAM)
        {
+         u32 len, chain_limit;
+
          if (ctx->max_dequeue <= sizeof (ctx->hdr))
            {
              ctx->max_len_to_snd = 0;
              return;
            }
+
          svm_fifo_peek (ctx->s->tx_fifo, 0, sizeof (ctx->hdr),
                         (u8 *) & ctx->hdr);
          ASSERT (ctx->hdr.data_length > ctx->hdr.data_offset);
-         ctx->max_dequeue = ctx->hdr.data_length - ctx->hdr.data_offset;
+         len = ctx->hdr.data_length - ctx->hdr.data_offset;
+
+         /* Process multiple dgrams if smaller than min (buf_space, mss).
+          * This avoids handling multiple dgrams if they require buffer
+          * chains */
+         chain_limit = clib_min (n_bytes_per_buf - TRANSPORT_MAX_HDRS_LEN,
+                                 ctx->sp.snd_mss);
+         if (ctx->hdr.data_length <= chain_limit)
+           {
+             u32 first_dgram_len, dgram_len, offset, max_offset;
+             session_dgram_hdr_t hdr;
+
+             ctx->sp.snd_mss = clib_min (ctx->sp.snd_mss, len);
+             offset = ctx->hdr.data_length + sizeof (session_dgram_hdr_t);
+             first_dgram_len = len;
+             max_offset = clib_min (ctx->max_dequeue, 16 << 10);
+
+             while (offset < max_offset)
+               {
+                 svm_fifo_peek (ctx->s->tx_fifo, offset, sizeof (ctx->hdr),
+                                (u8 *) & hdr);
+                 ASSERT (hdr.data_length > hdr.data_offset);
+                 dgram_len = hdr.data_length - hdr.data_offset;
+                 if (len + dgram_len > ctx->max_dequeue
+                     || first_dgram_len != dgram_len)
+                   break;
+                 len += dgram_len;
+                 offset += sizeof (hdr) + hdr.data_length;
+               }
+           }
+
+         ctx->max_dequeue = len;
        }
     }
   ASSERT (ctx->max_dequeue > 0);
 
   /* Ensure we're not writing more than transport window allows */
-  if (ctx->max_dequeue < ctx->snd_space)
+  if (ctx->max_dequeue < ctx->sp.snd_space)
     {
       /* Constrained by tx queue. Try to send only fully formed segments */
-      ctx->max_len_to_snd =
-       (ctx->max_dequeue > ctx->snd_mss) ?
-       ctx->max_dequeue - ctx->max_dequeue % ctx->snd_mss : ctx->max_dequeue;
+      ctx->max_len_to_snd = (ctx->max_dequeue > ctx->sp.snd_mss) ?
+       (ctx->max_dequeue - (ctx->max_dequeue % ctx->sp.snd_mss)) :
+       ctx->max_dequeue;
       /* TODO Nagle ? */
     }
   else
     {
       /* Expectation is that snd_space0 is already a multiple of snd_mss */
-      ctx->max_len_to_snd = ctx->snd_space;
+      ctx->max_len_to_snd = ctx->sp.snd_space;
     }
 
   /* Check if we're tx constrained by the node */
-  ctx->n_segs_per_evt = ceil ((f64) ctx->max_len_to_snd / ctx->snd_mss);
+  ctx->n_segs_per_evt = ceil ((f64) ctx->max_len_to_snd / ctx->sp.snd_mss);
   if (ctx->n_segs_per_evt > max_segs)
     {
       ctx->n_segs_per_evt = max_segs;
-      ctx->max_len_to_snd = max_segs * ctx->snd_mss;
+      ctx->max_len_to_snd = max_segs * ctx->sp.snd_mss;
     }
 
-  n_bytes_per_buf = vlib_buffer_get_default_data_size (vm);
   ASSERT (n_bytes_per_buf > TRANSPORT_MAX_HDRS_LEN);
-  n_bytes_per_seg = TRANSPORT_MAX_HDRS_LEN + ctx->snd_mss;
-  ctx->n_bufs_per_seg = ceil ((f64) n_bytes_per_seg / n_bytes_per_buf);
-  ctx->deq_per_buf = clib_min (ctx->snd_mss, n_bytes_per_buf);
-  ctx->deq_per_first_buf = clib_min (ctx->snd_mss,
+  if (ctx->n_segs_per_evt > 1)
+    {
+      u32 n_bytes_last_seg, n_bufs_last_seg;
+
+      n_bytes_per_seg = TRANSPORT_MAX_HDRS_LEN + ctx->sp.snd_mss;
+      n_bytes_last_seg = TRANSPORT_MAX_HDRS_LEN + ctx->max_len_to_snd
+       - ((ctx->n_segs_per_evt - 1) * ctx->sp.snd_mss);
+      ctx->n_bufs_per_seg = ceil ((f64) n_bytes_per_seg / n_bytes_per_buf);
+      n_bufs_last_seg = ceil ((f64) n_bytes_last_seg / n_bytes_per_buf);
+      ctx->n_bufs_needed = ((ctx->n_segs_per_evt - 1) * ctx->n_bufs_per_seg)
+       + n_bufs_last_seg;
+    }
+  else
+    {
+      n_bytes_per_seg = TRANSPORT_MAX_HDRS_LEN + ctx->max_len_to_snd;
+      ctx->n_bufs_per_seg = ceil ((f64) n_bytes_per_seg / n_bytes_per_buf);
+      ctx->n_bufs_needed = ctx->n_bufs_per_seg;
+    }
+
+  ctx->deq_per_buf = clib_min (ctx->sp.snd_mss, n_bytes_per_buf);
+  ctx->deq_per_first_buf = clib_min (ctx->sp.snd_mss,
                                     n_bytes_per_buf -
                                     TRANSPORT_MAX_HDRS_LEN);
 }
 
+always_inline void
+session_tx_maybe_reschedule (session_worker_t * wrk,
+                            session_tx_context_t * ctx,
+                            session_evt_elt_t * elt)
+{
+  session_t *s = ctx->s;
+
+  svm_fifo_unset_event (s->tx_fifo);
+  if (svm_fifo_max_dequeue_cons (s->tx_fifo) > ctx->sp.tx_offset)
+    if (svm_fifo_set_event (s->tx_fifo))
+      session_evt_add_head_old (wrk, elt);
+}
+
 always_inline int
-session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
-                               session_worker_t * wrk,
-                               session_event_t * e, int *n_tx_packets,
-                               u8 peek_data)
+session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
+                               vlib_node_runtime_t * node,
+                               session_evt_elt_t * elt,
+                               int *n_tx_packets, u8 peek_data)
 {
-  u32 next_index, next0, next1, *to_next, n_left_to_next, n_left, pbi;
-  u32 n_trace = vlib_get_trace_count (vm, node), n_bufs_needed = 0;
-  session_main_t *smm = &session_main;
+  u32 n_trace, n_left, pbi, next_index, max_burst;
   session_tx_context_t *ctx = &wrk->ctx;
+  session_main_t *smm = &session_main;
+  session_event_t *e = &elt->evt;
+  vlib_main_t *vm = wrk->vm;
   transport_proto_t tp;
   vlib_buffer_t *pb;
   u16 n_bufs, rv;
@@ -637,65 +950,101 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
   if (PREDICT_FALSE ((rv = session_tx_not_ready (ctx->s, peek_data))))
     {
       if (rv < 2)
-       vec_add1 (wrk->pending_event_vector, *e);
+       session_evt_add_old (wrk, elt);
       return SESSION_TX_NO_DATA;
     }
 
   next_index = smm->session_type_to_next[ctx->s->session_type];
-  next0 = next1 = next_index;
+  max_burst = SESSION_NODE_FRAME_SIZE - *n_tx_packets;
 
   tp = session_get_transport_proto (ctx->s);
   ctx->transport_vft = transport_protocol_get_vft (tp);
   ctx->tc = session_tx_get_transport (ctx, peek_data);
-  ctx->snd_mss = ctx->transport_vft->send_mss (ctx->tc);
 
   if (PREDICT_FALSE (e->event_type == SESSION_IO_EVT_TX_FLUSH))
     {
       if (ctx->transport_vft->flush_data)
        ctx->transport_vft->flush_data (ctx->tc);
+      e->event_type = SESSION_IO_EVT_TX;
     }
 
-  ctx->snd_space = transport_connection_snd_space (ctx->tc,
-                                                  vm->clib_time.
-                                                  last_cpu_time,
-                                                  ctx->snd_mss);
-  if (ctx->snd_space == 0 || ctx->snd_mss == 0)
+  if (ctx->s->flags & SESSION_F_CUSTOM_TX)
     {
-      vec_add1 (wrk->pending_event_vector, *e);
+      u32 n_custom_tx;
+      ctx->s->flags &= ~SESSION_F_CUSTOM_TX;
+      ctx->sp.max_burst_size = max_burst;
+      n_custom_tx = ctx->transport_vft->custom_tx (ctx->tc, &ctx->sp);
+      *n_tx_packets += n_custom_tx;
+      if (PREDICT_FALSE
+         (ctx->s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
+       return SESSION_TX_OK;
+      max_burst -= n_custom_tx;
+      if (!max_burst || (ctx->s->flags & SESSION_F_CUSTOM_TX))
+       {
+         session_evt_add_old (wrk, elt);
+         return SESSION_TX_OK;
+       }
+    }
+
+  transport_connection_snd_params (ctx->tc, &ctx->sp);
+
+  if (!ctx->sp.snd_space)
+    {
+      /* If the deschedule flag was set, remove session from scheduler.
+       * Transport is responsible for rescheduling this session. */
+      if (ctx->sp.flags & TRANSPORT_SND_F_DESCHED)
+       transport_connection_deschedule (ctx->tc);
+      /* Request to postpone the session, e.g., zero-wnd and transport
+       * is not currently probing */
+      else if (ctx->sp.flags & TRANSPORT_SND_F_POSTPONE)
+       session_evt_add_old (wrk, elt);
+      /* This flow queue is "empty" so it should be re-evaluated before
+       * the ones that have data to send. */
+      else
+       session_evt_add_head_old (wrk, elt);
+
       return SESSION_TX_NO_DATA;
     }
 
-  /* Allow enqueuing of a new event */
-  svm_fifo_unset_event (ctx->s->tx_fifo);
+  if (transport_connection_is_tx_paced (ctx->tc))
+    {
+      u32 snd_space = transport_connection_tx_pacer_burst (ctx->tc);
+      if (snd_space < TRANSPORT_PACER_MIN_BURST)
+       {
+         session_evt_add_head_old (wrk, elt);
+         return SESSION_TX_NO_DATA;
+       }
+      snd_space = clib_min (ctx->sp.snd_space, snd_space);
+      ctx->sp.snd_space = snd_space >= ctx->sp.snd_mss ?
+       snd_space - snd_space % ctx->sp.snd_mss : snd_space;
+    }
 
   /* Check how much we can pull. */
-  session_tx_set_dequeue_params (vm, ctx, VLIB_FRAME_SIZE - *n_tx_packets,
-                                peek_data);
+  session_tx_set_dequeue_params (vm, ctx, max_burst, peek_data);
 
   if (PREDICT_FALSE (!ctx->max_len_to_snd))
-    return SESSION_TX_NO_DATA;
+    {
+      transport_connection_tx_pacer_reset_bucket (ctx->tc, 0);
+      session_tx_maybe_reschedule (wrk, ctx, elt);
+      return SESSION_TX_NO_DATA;
+    }
 
-  n_bufs_needed = ctx->n_segs_per_evt * ctx->n_bufs_per_seg;
-  vec_validate_aligned (wrk->tx_buffers, n_bufs_needed - 1,
+  vec_validate_aligned (wrk->tx_buffers, ctx->n_bufs_needed - 1,
                        CLIB_CACHE_LINE_BYTES);
-  n_bufs = vlib_buffer_alloc (vm, wrk->tx_buffers, n_bufs_needed);
-  if (PREDICT_FALSE (n_bufs < n_bufs_needed))
+  n_bufs = vlib_buffer_alloc (vm, wrk->tx_buffers, ctx->n_bufs_needed);
+  if (PREDICT_FALSE (n_bufs < ctx->n_bufs_needed))
     {
       if (n_bufs)
        vlib_buffer_free (vm, wrk->tx_buffers, n_bufs);
-      vec_add1 (wrk->pending_event_vector, *e);
+      session_evt_add_head_old (wrk, elt);
+      vlib_node_increment_counter (wrk->vm, node->node_index,
+                                  SESSION_QUEUE_ERROR_NO_BUFFER, 1);
       return SESSION_TX_NO_BUFFERS;
     }
 
-  /*
-   * Write until we fill up a frame
-   */
-  vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
-  if (PREDICT_FALSE (ctx->n_segs_per_evt > n_left_to_next))
-    {
-      ctx->n_segs_per_evt = n_left_to_next;
-      ctx->max_len_to_snd = ctx->snd_mss * n_left_to_next;
-    }
+  if (transport_connection_is_tx_paced (ctx->tc))
+    transport_connection_tx_pacer_update_bytes (ctx->tc, ctx->max_len_to_snd);
+
   ctx->left_to_snd = ctx->max_len_to_snd;
   n_left = ctx->n_segs_per_evt;
 
@@ -711,8 +1060,8 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
       pb = vlib_get_buffer (vm, pbi);
       vlib_prefetch_buffer_header (pb, STORE);
 
-      to_next[0] = bi0 = wrk->tx_buffers[--n_bufs];
-      to_next[1] = bi1 = wrk->tx_buffers[--n_bufs];
+      bi0 = wrk->tx_buffers[--n_bufs];
+      bi1 = wrk->tx_buffers[--n_bufs];
 
       b0 = vlib_get_buffer (vm, bi0);
       b1 = vlib_get_buffer (vm, bi1);
@@ -723,16 +1072,15 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
       ctx->transport_vft->push_header (ctx->tc, b0);
       ctx->transport_vft->push_header (ctx->tc, b1);
 
-      to_next += 2;
-      n_left_to_next -= 2;
       n_left -= 2;
 
       VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b1);
 
-      vlib_validate_buffer_enqueue_x2 (vm, node, next_index, to_next,
-                                      n_left_to_next, bi0, bi1, next0,
-                                      next1);
+      vec_add1 (wrk->pending_tx_buffers, bi0);
+      vec_add1 (wrk->pending_tx_buffers, bi1);
+      vec_add1 (wrk->pending_tx_nexts, next_index);
+      vec_add1 (wrk->pending_tx_nexts, next_index);
     }
   while (n_left)
     {
@@ -746,7 +1094,7 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
          vlib_prefetch_buffer_header (pb, STORE);
        }
 
-      to_next[0] = bi0 = wrk->tx_buffers[--n_bufs];
+      bi0 = wrk->tx_buffers[--n_bufs];
       b0 = vlib_get_buffer (vm, bi0);
       session_tx_fill_buffer (vm, ctx, b0, &n_bufs, peek_data);
 
@@ -754,270 +1102,493 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
        * total_length_not_including_first_buffer are updated */
       ctx->transport_vft->push_header (ctx->tc, b0);
 
-      to_next += 1;
-      n_left_to_next -= 1;
       n_left -= 1;
 
       VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
 
-      vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
-                                      n_left_to_next, bi0, next0);
+      vec_add1 (wrk->pending_tx_buffers, bi0);
+      vec_add1 (wrk->pending_tx_nexts, next_index);
     }
 
-  if (PREDICT_FALSE (n_trace > 0))
-    session_tx_trace_frame (vm, node, next_index, to_next,
+  if (PREDICT_FALSE ((n_trace = vlib_get_trace_count (vm, node)) > 0))
+    session_tx_trace_frame (vm, node, next_index, wrk->pending_tx_buffers,
                            ctx->n_segs_per_evt, ctx->s, n_trace);
+
   if (PREDICT_FALSE (n_bufs))
-    {
-      clib_warning ("not all buffers consumed");
-      vlib_buffer_free (vm, wrk->tx_buffers, n_bufs);
-    }
+    vlib_buffer_free (vm, wrk->tx_buffers, n_bufs);
+
   *n_tx_packets += ctx->n_segs_per_evt;
-  transport_connection_update_tx_stats (ctx->tc, ctx->max_len_to_snd);
-  vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 
-  /* If we couldn't dequeue all bytes mark as partially read */
+  SESSION_EVT (SESSION_EVT_DEQ, ctx->s, ctx->max_len_to_snd, ctx->max_dequeue,
+              ctx->s->tx_fifo->has_event, wrk->last_vlib_time);
+
   ASSERT (ctx->left_to_snd == 0);
+
+  /* If we couldn't dequeue all bytes reschedule as old flow. Otherwise,
+   * check if application enqueued more data and reschedule accordingly */
   if (ctx->max_len_to_snd < ctx->max_dequeue)
-    if (svm_fifo_set_event (ctx->s->tx_fifo))
-      vec_add1 (wrk->pending_event_vector, *e);
+    session_evt_add_old (wrk, elt);
+  else
+    session_tx_maybe_reschedule (wrk, ctx, elt);
 
-  if (!peek_data && ctx->transport_vft->tx_type == TRANSPORT_TX_DGRAM)
+  if (!peek_data)
     {
-      /* Fix dgram pre header */
-      if (ctx->max_len_to_snd < ctx->max_dequeue)
-       svm_fifo_overwrite_head (ctx->s->tx_fifo, (u8 *) & ctx->hdr,
-                                sizeof (session_dgram_pre_hdr_t));
-      /* More data needs to be read */
-      else if (svm_fifo_max_dequeue (ctx->s->tx_fifo) > 0)
-       if (svm_fifo_set_event (ctx->s->tx_fifo))
-         vec_add1 (wrk->pending_event_vector, *e);
+      u32 n_dequeued = ctx->max_len_to_snd;
+      if (ctx->transport_vft->transport_options.tx_type == TRANSPORT_TX_DGRAM)
+       n_dequeued += ctx->n_segs_per_evt * SESSION_CONN_HDR_LEN;
+      if (svm_fifo_needs_deq_ntf (ctx->s->tx_fifo, n_dequeued))
+       session_dequeue_notify (ctx->s);
     }
   return SESSION_TX_OK;
 }
 
 int
-session_tx_fifo_peek_and_snd (vlib_main_t * vm, vlib_node_runtime_t * node,
-                             session_worker_t * wrk,
-                             session_event_t * e, int *n_tx_pkts)
+session_tx_fifo_peek_and_snd (session_worker_t * wrk,
+                             vlib_node_runtime_t * node,
+                             session_evt_elt_t * e, int *n_tx_packets)
 {
-  return session_tx_fifo_read_and_snd_i (vm, node, wrk, e, n_tx_pkts, 1);
+  return session_tx_fifo_read_and_snd_i (wrk, node, e, n_tx_packets, 1);
 }
 
 int
-session_tx_fifo_dequeue_and_snd (vlib_main_t * vm, vlib_node_runtime_t * node,
-                                session_worker_t * wrk,
-                                session_event_t * e, int *n_tx_pkts)
+session_tx_fifo_dequeue_and_snd (session_worker_t * wrk,
+                                vlib_node_runtime_t * node,
+                                session_evt_elt_t * e, int *n_tx_packets)
 {
-  return session_tx_fifo_read_and_snd_i (vm, node, wrk, e, n_tx_pkts, 0);
+  return session_tx_fifo_read_and_snd_i (wrk, node, e, n_tx_packets, 0);
 }
 
 int
-session_tx_fifo_dequeue_internal (vlib_main_t * vm,
+session_tx_fifo_dequeue_internal (session_worker_t * wrk,
                                  vlib_node_runtime_t * node,
-                                 session_worker_t * wrk,
-                                 session_event_t * e, int *n_tx_pkts)
+                                 session_evt_elt_t * elt, int *n_tx_packets)
 {
+  transport_send_params_t *sp = &wrk->ctx.sp;
   session_t *s = wrk->ctx.s;
-  application_t *app;
+  u32 n_packets;
 
-  if (PREDICT_FALSE (s->session_state == SESSION_STATE_CLOSED))
+  if (PREDICT_FALSE (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
     return 0;
-  app = application_get (s->t_app_index);
-  svm_fifo_unset_event (s->tx_fifo);
-  return app->cb_fns.builtin_app_tx_callback (s);
+
+  /* Clear custom-tx flag used to request reschedule for tx */
+  s->flags &= ~SESSION_F_CUSTOM_TX;
+
+  sp->max_burst_size = clib_min (SESSION_NODE_FRAME_SIZE - *n_tx_packets,
+                                TRANSPORT_PACER_MAX_BURST_PKTS);
+
+  n_packets = transport_custom_tx (session_get_transport_proto (s), s, sp);
+  *n_tx_packets += n_packets;
+
+  if (s->flags & SESSION_F_CUSTOM_TX)
+    {
+      session_evt_add_old (wrk, elt);
+    }
+  else if (!(sp->flags & TRANSPORT_SND_F_DESCHED))
+    {
+      svm_fifo_unset_event (s->tx_fifo);
+      if (svm_fifo_max_dequeue_cons (s->tx_fifo))
+       if (svm_fifo_set_event (s->tx_fifo))
+         session_evt_add_head_old (wrk, elt);
+    }
+
+  if (sp->max_burst_size &&
+      svm_fifo_needs_deq_ntf (s->tx_fifo, sp->max_burst_size))
+    session_dequeue_notify (s);
+
+  return n_packets;
 }
 
 always_inline session_t *
-session_event_get_session (session_event_t * e, u8 thread_index)
+session_event_get_session (session_worker_t * wrk, session_event_t * e)
 {
-  return session_get_if_valid (e->fifo->master_session_index, thread_index);
+  if (PREDICT_FALSE (pool_is_free_index (wrk->sessions, e->session_index)))
+    return 0;
+
+  ASSERT (session_is_valid (e->session_index, wrk->vm->thread_index));
+  return pool_elt_at_index (wrk->sessions, e->session_index);
+}
+
+always_inline void
+session_event_dispatch_ctrl (session_worker_t * wrk, session_evt_elt_t * elt)
+{
+  clib_llist_index_t ei;
+  void (*fp) (void *);
+  session_event_t *e;
+  session_t *s;
+
+  ei = clib_llist_entry_index (wrk->event_elts, elt);
+  e = &elt->evt;
+
+  switch (e->event_type)
+    {
+    case SESSION_CTRL_EVT_RPC:
+      fp = e->rpc_args.fp;
+      (*fp) (e->rpc_args.arg);
+      break;
+    case SESSION_CTRL_EVT_CLOSE:
+      s = session_get_from_handle_if_valid (e->session_handle);
+      if (PREDICT_FALSE (!s))
+       break;
+      session_transport_close (s);
+      break;
+    case SESSION_CTRL_EVT_RESET:
+      s = session_get_from_handle_if_valid (e->session_handle);
+      if (PREDICT_FALSE (!s))
+       break;
+      session_transport_reset (s);
+      break;
+    case SESSION_CTRL_EVT_LISTEN:
+      session_mq_listen_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_LISTEN_URI:
+      session_mq_listen_uri_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_UNLISTEN:
+      session_mq_unlisten_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_CONNECT:
+      session_mq_connect_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_CONNECT_URI:
+      session_mq_connect_uri_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_DISCONNECT:
+      session_mq_disconnect_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_DISCONNECTED:
+      session_mq_disconnected_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_ACCEPTED_REPLY:
+      session_mq_accepted_reply_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_DISCONNECTED_REPLY:
+      session_mq_disconnected_reply_handler (session_evt_ctrl_data (wrk,
+                                                                   elt));
+      break;
+    case SESSION_CTRL_EVT_RESET_REPLY:
+      session_mq_reset_reply_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_WORKER_UPDATE:
+      session_mq_worker_update_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_APP_DETACH:
+      app_mq_detach_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    case SESSION_CTRL_EVT_APP_WRK_RPC:
+      session_mq_app_wrk_rpc_handler (session_evt_ctrl_data (wrk, elt));
+      break;
+    default:
+      clib_warning ("unhandled event type %d", e->event_type);
+    }
+
+  /* Regrab elements in case pool moved */
+  elt = pool_elt_at_index (wrk->event_elts, ei);
+  if (!clib_llist_elt_is_linked (elt, evt_list))
+    {
+      e = &elt->evt;
+      if (e->event_type >= SESSION_CTRL_EVT_BOUND)
+       session_evt_ctrl_data_free (wrk, elt);
+      session_evt_elt_free (wrk, elt);
+    }
+  SESSION_EVT (SESSION_EVT_COUNTS, CNT_CTRL_EVTS, 1, wrk);
+}
+
+always_inline void
+session_event_dispatch_io (session_worker_t * wrk, vlib_node_runtime_t * node,
+                          session_evt_elt_t * elt, int *n_tx_packets)
+{
+  session_main_t *smm = &session_main;
+  app_worker_t *app_wrk;
+  clib_llist_index_t ei;
+  session_event_t *e;
+  session_t *s;
+
+  ei = clib_llist_entry_index (wrk->event_elts, elt);
+  e = &elt->evt;
+
+  switch (e->event_type)
+    {
+    case SESSION_IO_EVT_TX_FLUSH:
+    case SESSION_IO_EVT_TX:
+      s = session_event_get_session (wrk, e);
+      if (PREDICT_FALSE (!s))
+       break;
+      CLIB_PREFETCH (s->tx_fifo, 2 * CLIB_CACHE_LINE_BYTES, LOAD);
+      wrk->ctx.s = s;
+      /* Spray packets in per session type frames, since they go to
+       * different nodes */
+      (smm->session_tx_fns[s->session_type]) (wrk, node, elt, n_tx_packets);
+      break;
+    case SESSION_IO_EVT_RX:
+      s = session_event_get_session (wrk, e);
+      if (!s)
+       break;
+      transport_app_rx_evt (session_get_transport_proto (s),
+                           s->connection_index, s->thread_index);
+      break;
+    case SESSION_IO_EVT_BUILTIN_RX:
+      s = session_event_get_session (wrk, e);
+      if (PREDICT_FALSE (!s || s->session_state >= SESSION_STATE_CLOSING))
+       break;
+      svm_fifo_unset_event (s->rx_fifo);
+      app_wrk = app_worker_get (s->app_wrk_index);
+      app_worker_builtin_rx (app_wrk, s);
+      break;
+    case SESSION_IO_EVT_BUILTIN_TX:
+      s = session_get_from_handle_if_valid (e->session_handle);
+      wrk->ctx.s = s;
+      if (PREDICT_TRUE (s != 0))
+       session_tx_fifo_dequeue_internal (wrk, node, elt, n_tx_packets);
+      break;
+    default:
+      clib_warning ("unhandled event type %d", e->event_type);
+    }
+
+  SESSION_EVT (SESSION_IO_EVT_COUNTS, e->event_type, 1, wrk);
+
+  /* Regrab elements in case pool moved */
+  elt = pool_elt_at_index (wrk->event_elts, ei);
+  if (!clib_llist_elt_is_linked (elt, evt_list))
+    session_evt_elt_free (wrk, elt);
+}
+
+/* *INDENT-OFF* */
+static const u32 session_evt_msg_sizes[] = {
+#define _(symc, sym)                                                   \
+  [SESSION_CTRL_EVT_ ## symc] = sizeof (session_ ## sym ##_msg_t),
+  foreach_session_ctrl_evt
+#undef _
+};
+/* *INDENT-ON* */
+
+always_inline void
+session_evt_add_to_list (session_worker_t * wrk, session_event_t * evt)
+{
+  session_evt_elt_t *elt;
+
+  if (evt->event_type >= SESSION_CTRL_EVT_RPC)
+    {
+      elt = session_evt_alloc_ctrl (wrk);
+      if (evt->event_type >= SESSION_CTRL_EVT_BOUND)
+       {
+         elt->evt.ctrl_data_index = session_evt_ctrl_data_alloc (wrk);
+         elt->evt.event_type = evt->event_type;
+         clib_memcpy_fast (session_evt_ctrl_data (wrk, elt), evt->data,
+                           session_evt_msg_sizes[evt->event_type]);
+       }
+      else
+       {
+         /* Internal control events fit into io events footprint */
+         clib_memcpy_fast (&elt->evt, evt, sizeof (elt->evt));
+       }
+    }
+  else
+    {
+      elt = session_evt_alloc_new (wrk);
+      clib_memcpy_fast (&elt->evt, evt, sizeof (elt->evt));
+    }
 }
 
 static void
-session_update_dispatch_period (session_worker_t * wrk, f64 now,
-                               u32 thread_index)
+session_flush_pending_tx_buffers (session_worker_t * wrk,
+                                 vlib_node_runtime_t * node)
+{
+  vlib_buffer_enqueue_to_next (wrk->vm, node, wrk->pending_tx_buffers,
+                              wrk->pending_tx_nexts,
+                              vec_len (wrk->pending_tx_nexts));
+  vec_reset_length (wrk->pending_tx_buffers);
+  vec_reset_length (wrk->pending_tx_nexts);
+}
+
+int
+session_wrk_handle_mq (session_worker_t *wrk, svm_msg_q_t *mq)
 {
-  if (wrk->last_tx_packets)
+  svm_msg_q_msg_t _msg, *msg = &_msg;
+  u32 i, n_to_dequeue = 0;
+  session_event_t *evt;
+
+  n_to_dequeue = svm_msg_q_size (mq);
+  for (i = 0; i < n_to_dequeue; i++)
     {
-      f64 sample = now - wrk->last_vlib_time;
-      wrk->dispatch_period = (wrk->dispatch_period + sample) * 0.5;
+      svm_msg_q_sub_raw (mq, msg);
+      evt = svm_msg_q_msg_data (mq, msg);
+      session_evt_add_to_list (wrk, evt);
+      svm_msg_q_free_msg (mq, msg);
+    }
+
+  return n_to_dequeue;
+}
+
+static void
+session_wrk_timerfd_update (session_worker_t *wrk, u64 time_ns)
+{
+  struct itimerspec its;
+
+  its.it_value.tv_sec = 0;
+  its.it_value.tv_nsec = time_ns;
+  its.it_interval.tv_sec = 0;
+  its.it_interval.tv_nsec = its.it_value.tv_nsec;
+
+  if (timerfd_settime (wrk->timerfd, 0, &its, NULL) == -1)
+    clib_warning ("timerfd_settime");
+}
+
+always_inline u64
+session_wrk_tfd_timeout (session_wrk_state_t state, u32 thread_index)
+{
+  if (state == SESSION_WRK_INTERRUPT)
+    return thread_index ? 1e6 : vlib_num_workers () ? 5e8 : 1e6;
+  else if (state == SESSION_WRK_IDLE)
+    return thread_index ? 1e8 : vlib_num_workers () ? 5e8 : 1e8;
+  else
+    return 0;
+}
+
+static inline void
+session_wrk_state_update (session_worker_t *wrk, session_wrk_state_t state)
+{
+  u64 time_ns;
+
+  wrk->state = state;
+  time_ns = session_wrk_tfd_timeout (state, wrk->vm->thread_index);
+  session_wrk_timerfd_update (wrk, time_ns);
+}
+
+static void
+session_wrk_update_state (session_worker_t *wrk)
+{
+  vlib_main_t *vm = wrk->vm;
+
+  if (wrk->state == SESSION_WRK_POLLING)
+    {
+      if (pool_elts (wrk->event_elts) == 3 &&
+         vlib_last_vectors_per_main_loop (vm) < 1)
+       {
+         session_wrk_state_update (wrk, SESSION_WRK_INTERRUPT);
+         vlib_node_set_state (vm, session_queue_node.index,
+                              VLIB_NODE_STATE_INTERRUPT);
+       }
+    }
+  else if (wrk->state == SESSION_WRK_INTERRUPT)
+    {
+      if (pool_elts (wrk->event_elts) > 3 ||
+         vlib_last_vectors_per_main_loop (vm) > 1)
+       {
+         session_wrk_state_update (wrk, SESSION_WRK_POLLING);
+         vlib_node_set_state (vm, session_queue_node.index,
+                              VLIB_NODE_STATE_POLLING);
+       }
+      else if (PREDICT_FALSE (!pool_elts (wrk->sessions)))
+       {
+         session_wrk_state_update (wrk, SESSION_WRK_IDLE);
+       }
+    }
+  else
+    {
+      if (pool_elts (wrk->event_elts))
+       {
+         session_wrk_state_update (wrk, SESSION_WRK_INTERRUPT);
+       }
     }
-  wrk->last_vlib_time = now;
 }
 
 static uword
 session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
                       vlib_frame_t * frame)
 {
+  u32 thread_index = vm->thread_index, __clib_unused n_evts;
+  session_evt_elt_t *elt, *ctrl_he, *new_he, *old_he;
   session_main_t *smm = vnet_get_session_main ();
-  u32 thread_index = vm->thread_index, n_to_dequeue, n_events;
   session_worker_t *wrk = &smm->wrk[thread_index];
-  session_event_t *e, *fifo_events;
-  svm_msg_q_msg_t _msg, *msg = &_msg;
-  f64 now = vlib_time_now (vm);
-  int n_tx_packets = 0, i, rv;
-  app_worker_t *app_wrk;
-  application_t *app;
-  svm_msg_q_t *mq;
-  void (*fp) (void *);
+  clib_llist_index_t ei, next_ei, old_ti;
+  int n_tx_packets;
 
-  SESSION_EVT_DBG (SESSION_EVT_POLL_GAP_TRACK, smm, thread_index);
+  SESSION_EVT (SESSION_EVT_DISPATCH_START, wrk);
+
+  session_wrk_update_time (wrk, vlib_time_now (vm));
 
   /*
    *  Update transport time
    */
-  session_update_dispatch_period (wrk, now, thread_index);
-  transport_update_time (now, thread_index);
+  transport_update_time (wrk->last_vlib_time, thread_index);
+  n_tx_packets = vec_len (wrk->pending_tx_buffers);
+  SESSION_EVT (SESSION_EVT_DSP_CNTRS, UPDATE_TIME, wrk);
+
+  /*
+   *  Dequeue new internal mq events
+   */
 
-  SESSION_EVT_DBG (SESSION_EVT_DEQ_NODE, 0);
+  n_evts = session_wrk_handle_mq (wrk, wrk->vpp_event_queue);
+  SESSION_EVT (SESSION_EVT_DSP_CNTRS, MQ_DEQ, wrk, n_evts);
 
-  /* Make sure postponed events are handled first */
-  fifo_events = wrk->free_event_vector;
-  vec_append (fifo_events, wrk->postponed_event_vector);
-  _vec_len (wrk->postponed_event_vector) = 0;
+  /*
+   * Handle control events
+   */
 
-  /* Try to dequeue what is available. Don't wait for lock.
-   * XXX: we may need priorities here */
-  mq = wrk->vpp_event_queue;
-  n_to_dequeue = svm_msg_q_size (mq);
-  if (n_to_dequeue && svm_msg_q_try_lock (mq) == 0)
+  ctrl_he = pool_elt_at_index (wrk->event_elts, wrk->ctrl_head);
+
+  clib_llist_foreach_safe (wrk->event_elts, evt_list, ctrl_he, elt, ({
+    clib_llist_remove (wrk->event_elts, evt_list, elt);
+    session_event_dispatch_ctrl (wrk, elt);
+  }));
+
+  SESSION_EVT (SESSION_EVT_DSP_CNTRS, CTRL_EVTS, wrk);
+
+  /*
+   * Handle the new io events.
+   */
+
+  new_he = pool_elt_at_index (wrk->event_elts, wrk->new_head);
+  old_he = pool_elt_at_index (wrk->event_elts, wrk->old_head);
+  old_ti = clib_llist_prev_index (old_he, evt_list);
+
+  ei = clib_llist_next_index (new_he, evt_list);
+  while (ei != wrk->new_head && n_tx_packets < SESSION_NODE_FRAME_SIZE)
     {
-      for (i = 0; i < n_to_dequeue; i++)
-       {
-         vec_add2 (fifo_events, e, 1);
-         svm_msg_q_sub_w_lock (mq, msg);
-         /* Works because reply messages are smaller than a session evt.
-          * If we ever need to support bigger messages this needs to be
-          * fixed */
-         clib_memcpy_fast (e, svm_msg_q_msg_data (mq, msg), sizeof (*e));
-         svm_msg_q_free_msg (mq, msg);
-       }
-      svm_msg_q_unlock (mq);
+      elt = pool_elt_at_index (wrk->event_elts, ei);
+      ei = clib_llist_next_index (elt, evt_list);
+      clib_llist_remove (wrk->event_elts, evt_list, elt);
+      session_event_dispatch_io (wrk, node, elt, &n_tx_packets);
     }
 
-  vec_append (fifo_events, wrk->pending_event_vector);
-  vec_append (fifo_events, wrk->pending_disconnects);
+  SESSION_EVT (SESSION_EVT_DSP_CNTRS, NEW_IO_EVTS, wrk);
 
-  _vec_len (wrk->pending_event_vector) = 0;
-  _vec_len (wrk->pending_disconnects) = 0;
-
-  n_events = vec_len (fifo_events);
-  if (PREDICT_FALSE (!n_events))
-    return 0;
+  /*
+   * Handle the old io events, if we had any prior to processing the new ones
+   */
 
-  for (i = 0; i < n_events; i++)
+  if (old_ti != wrk->old_head)
     {
-      session_t *s;            /* $$$ prefetch 1 ahead maybe */
-      session_event_t *e;
-      u8 need_tx_ntf;
+      old_he = pool_elt_at_index (wrk->event_elts, wrk->old_head);
+      ei = clib_llist_next_index (old_he, evt_list);
 
-      e = &fifo_events[i];
-      switch (e->event_type)
+      while (n_tx_packets < SESSION_NODE_FRAME_SIZE)
        {
-       case SESSION_IO_EVT_TX_FLUSH:
-       case SESSION_IO_EVT_TX:
-         /* Don't try to send more that one frame per dispatch cycle */
-         if (n_tx_packets == VLIB_FRAME_SIZE)
-           {
-             vec_add1 (wrk->postponed_event_vector, *e);
-             break;
-           }
+         elt = pool_elt_at_index (wrk->event_elts, ei);
+         next_ei = clib_llist_next_index (elt, evt_list);
+         clib_llist_remove (wrk->event_elts, evt_list, elt);
 
-         s = session_event_get_session (e, thread_index);
-         if (PREDICT_FALSE (!s))
-           {
-             clib_warning ("session was freed!");
-             continue;
-           }
-         wrk->ctx.s = s;
-         /* Spray packets in per session type frames, since they go to
-          * different nodes */
-         rv = (smm->session_tx_fns[s->session_type]) (vm, node, wrk, e,
-                                                      &n_tx_packets);
-         if (PREDICT_TRUE (rv == SESSION_TX_OK))
-           {
-             need_tx_ntf = svm_fifo_needs_tx_ntf (s->tx_fifo,
-                                                  wrk->ctx.max_len_to_snd);
-             if (PREDICT_FALSE (need_tx_ntf))
-               session_dequeue_notify (s);
-           }
-         else if (PREDICT_FALSE (rv == SESSION_TX_NO_BUFFERS))
-           {
-             vlib_node_increment_counter (vm, node->node_index,
-                                          SESSION_QUEUE_ERROR_NO_BUFFER, 1);
-             continue;
-           }
-         break;
-       case SESSION_CTRL_EVT_CLOSE:
-         s = session_get_from_handle_if_valid (e->session_handle);
-         if (PREDICT_FALSE (!s))
-           break;
+         session_event_dispatch_io (wrk, node, elt, &n_tx_packets);
 
-         /* Make sure session disconnects run after the pending list is
-          * drained, i.e., postpone if the first time. If not the first
-          * and the tx queue is still not empty, try to wait for some
-          * dispatch cycles */
-         if (!e->postponed
-             || (e->postponed < 200 && svm_fifo_max_dequeue (s->tx_fifo)))
-           {
-             e->postponed += 1;
-             vec_add1 (wrk->pending_disconnects, *e);
-             continue;
-           }
+         if (ei == old_ti)
+           break;
 
-         session_transport_close (s);
-         break;
-       case SESSION_IO_EVT_BUILTIN_RX:
-         s = session_event_get_session (e, thread_index);
-         if (PREDICT_FALSE (!s || s->session_state >= SESSION_STATE_CLOSING))
-           continue;
-         svm_fifo_unset_event (s->rx_fifo);
-         app_wrk = app_worker_get (s->app_wrk_index);
-         app = application_get (app_wrk->app_index);
-         app->cb_fns.builtin_app_rx_callback (s);
-         break;
-       case SESSION_IO_EVT_BUILTIN_TX:
-         s = session_get_from_handle_if_valid (e->session_handle);
-         wrk->ctx.s = s;
-         if (PREDICT_TRUE (s != 0))
-           session_tx_fifo_dequeue_internal (vm, node, wrk, e,
-                                             &n_tx_packets);
-         break;
-       case SESSION_CTRL_EVT_RPC:
-         fp = e->rpc_args.fp;
-         (*fp) (e->rpc_args.arg);
-         break;
-       case SESSION_CTRL_EVT_DISCONNECTED:
-         session_mq_disconnected_handler (e->data);
-         break;
-       case SESSION_CTRL_EVT_ACCEPTED_REPLY:
-         session_mq_accepted_reply_handler (e->data);
-         break;
-       case SESSION_CTRL_EVT_CONNECTED_REPLY:
-         break;
-       case SESSION_CTRL_EVT_DISCONNECTED_REPLY:
-         session_mq_disconnected_reply_handler (e->data);
-         break;
-       case SESSION_CTRL_EVT_RESET_REPLY:
-         session_mq_reset_reply_handler (e->data);
-         break;
-       case SESSION_CTRL_EVT_WORKER_UPDATE:
-         session_mq_worker_update_handler (e->data);
-         break;
-       default:
-         clib_warning ("unhandled event type %d", e->event_type);
-       }
+         ei = next_ei;
+       };
     }
 
-  _vec_len (fifo_events) = 0;
-  wrk->free_event_vector = fifo_events;
-  wrk->last_tx_packets = n_tx_packets;
+  SESSION_EVT (SESSION_EVT_DSP_CNTRS, OLD_IO_EVTS, wrk);
+
+  if (vec_len (wrk->pending_tx_buffers))
+    session_flush_pending_tx_buffers (wrk, node);
 
   vlib_node_increment_counter (vm, session_queue_node.index,
                               SESSION_QUEUE_ERROR_TX, n_tx_packets);
 
-  SESSION_EVT_DBG (SESSION_EVT_DISPATCH_END, smm, thread_index);
+  SESSION_EVT (SESSION_EVT_DISPATCH_END, wrk, n_tx_packets);
+
+  if (wrk->flags & SESSION_WRK_F_ADAPTIVE)
+    session_wrk_update_state (wrk);
 
   return n_tx_packets;
 }
@@ -1026,6 +1597,7 @@ session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 VLIB_REGISTER_NODE (session_queue_node) =
 {
   .function = session_queue_node_fn,
+  .flags = VLIB_NODE_FLAG_TRACE_SUPPORTED,
   .name = "session-queue",
   .format_trace = format_session_queue_trace,
   .type = VLIB_NODE_TYPE_INPUT,
@@ -1035,146 +1607,50 @@ VLIB_REGISTER_NODE (session_queue_node) =
 };
 /* *INDENT-ON* */
 
-void
-dump_thread_0_event_queue (void)
+static clib_error_t *
+session_wrk_tfd_read_ready (clib_file_t *cf)
 {
-  session_main_t *smm = vnet_get_session_main ();
-  vlib_main_t *vm = &vlib_global_main;
-  u32 my_thread_index = vm->thread_index;
-  session_event_t _e, *e = &_e;
-  svm_msg_q_ring_t *ring;
-  session_t *s0;
-  svm_msg_q_msg_t *msg;
-  svm_msg_q_t *mq;
-  int i, index;
-
-  mq = smm->wrk[my_thread_index].vpp_event_queue;
-  index = mq->q->head;
-
-  for (i = 0; i < mq->q->cursize; i++)
-    {
-      msg = (svm_msg_q_msg_t *) (&mq->q->data[0] + mq->q->elsize * index);
-      ring = svm_msg_q_ring (mq, msg->ring_index);
-      clib_memcpy_fast (e, svm_msg_q_msg_data (mq, msg), ring->elsize);
-
-      switch (e->event_type)
-       {
-       case SESSION_IO_EVT_TX:
-         s0 = session_event_get_session (e, my_thread_index);
-         fformat (stdout, "[%04d] TX session %d\n", i, s0->session_index);
-         break;
-
-       case SESSION_CTRL_EVT_CLOSE:
-         s0 = session_get_from_handle (e->session_handle);
-         fformat (stdout, "[%04d] disconnect session %d\n", i,
-                  s0->session_index);
-         break;
-
-       case SESSION_IO_EVT_BUILTIN_RX:
-         s0 = session_event_get_session (e, my_thread_index);
-         fformat (stdout, "[%04d] builtin_rx %d\n", i, s0->session_index);
-         break;
-
-       case SESSION_CTRL_EVT_RPC:
-         fformat (stdout, "[%04d] RPC call %llx with %llx\n",
-                  i, (u64) (uword) (e->rpc_args.fp),
-                  (u64) (uword) (e->rpc_args.arg));
-         break;
-
-       default:
-         fformat (stdout, "[%04d] unhandled event type %d\n",
-                  i, e->event_type);
-         break;
-       }
-
-      index++;
-
-      if (index == mq->q->maxsize)
-       index = 0;
-    }
+  session_worker_t *wrk = session_main_get_worker (cf->private_data);
+  u64 buf;
+  int rv;
+
+  vlib_node_set_interrupt_pending (wrk->vm, session_queue_node.index);
+  rv = read (wrk->timerfd, &buf, sizeof (buf));
+  if (rv < 0 && errno != EAGAIN)
+    clib_unix_warning ("failed");
+  return 0;
 }
 
-static u8
-session_node_cmp_event (session_event_t * e, svm_fifo_t * f)
+static clib_error_t *
+session_wrk_tfd_write_ready (clib_file_t *cf)
 {
-  session_t *s;
-  switch (e->event_type)
-    {
-    case SESSION_IO_EVT_RX:
-    case SESSION_IO_EVT_TX:
-    case SESSION_IO_EVT_BUILTIN_RX:
-      if (e->fifo == f)
-       return 1;
-      break;
-    case SESSION_CTRL_EVT_CLOSE:
-      break;
-    case SESSION_CTRL_EVT_RPC:
-      s = session_get_from_handle (e->session_handle);
-      if (!s)
-       {
-         clib_warning ("session has event but doesn't exist!");
-         break;
-       }
-      if (s->rx_fifo == f || s->tx_fifo == f)
-       return 1;
-      break;
-    default:
-      break;
-    }
   return 0;
 }
 
-u8
-session_node_lookup_fifo_event (svm_fifo_t * f, session_event_t * e)
+void
+session_wrk_enable_adaptive_mode (session_worker_t *wrk)
 {
-  session_event_t *pending_event_vector, *evt;
-  session_worker_t *wrk;
-  int i, index, found = 0;
-  svm_msg_q_msg_t *msg;
-  svm_msg_q_ring_t *ring;
-  svm_msg_q_t *mq;
-  u8 thread_index;
+  u32 thread_index = wrk->vm->thread_index;
+  clib_file_t template = { 0 };
 
-  ASSERT (e);
-  thread_index = f->master_thread_index;
-  wrk = session_main_get_worker (thread_index);
+  if ((wrk->timerfd = timerfd_create (CLOCK_MONOTONIC, TFD_NONBLOCK)) < 0)
+    clib_warning ("timerfd_create");
 
-  /*
-   * Search evt queue
-   */
-  mq = wrk->vpp_event_queue;
-  index = mq->q->head;
-  for (i = 0; i < mq->q->cursize; i++)
-    {
-      msg = (svm_msg_q_msg_t *) (&mq->q->data[0] + mq->q->elsize * index);
-      ring = svm_msg_q_ring (mq, msg->ring_index);
-      clib_memcpy_fast (e, svm_msg_q_msg_data (mq, msg), ring->elsize);
-      found = session_node_cmp_event (e, f);
-      if (found)
-       return 1;
-      if (++index == mq->q->maxsize)
-       index = 0;
-    }
-  /*
-   * Search pending events vector
-   */
-  pending_event_vector = wrk->pending_event_vector;
-  vec_foreach (evt, pending_event_vector)
-  {
-    found = session_node_cmp_event (evt, f);
-    if (found)
-      {
-       clib_memcpy_fast (e, evt, sizeof (*evt));
-       break;
-      }
-  }
-  return found;
+  template.read_function = session_wrk_tfd_read_ready;
+  template.write_function = session_wrk_tfd_write_ready;
+  template.file_descriptor = wrk->timerfd;
+  template.private_data = thread_index;
+  template.polling_thread_index = thread_index;
+  template.description = format (0, "session-wrk-tfd-%u", thread_index);
+
+  wrk->timerfd_file = clib_file_add (&file_main, &template);
+  wrk->flags |= SESSION_WRK_F_ADAPTIVE;
 }
 
 static clib_error_t *
 session_queue_exit (vlib_main_t * vm)
 {
-  if (vec_len (vlib_mains) < 2)
+  if (vlib_get_n_threads () < 2)
     return 0;
 
   /*
@@ -1190,33 +1666,42 @@ session_queue_exit (vlib_main_t * vm)
 
 VLIB_MAIN_LOOP_EXIT_FUNCTION (session_queue_exit);
 
+static uword
+session_queue_run_on_main (vlib_main_t * vm)
+{
+  vlib_node_runtime_t *node;
+
+  node = vlib_node_get_runtime (vm, session_queue_node.index);
+  return session_queue_node_fn (vm, node, 0);
+}
+
 static uword
 session_queue_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
                       vlib_frame_t * f)
 {
-  f64 now, timeout = 1.0;
   uword *event_data = 0;
+  f64 timeout = 1.0;
   uword event_type;
 
   while (1)
     {
       vlib_process_wait_for_event_or_clock (vm, timeout);
-      now = vlib_time_now (vm);
       event_type = vlib_process_get_events (vm, (uword **) & event_data);
 
       switch (event_type)
        {
-       case SESSION_Q_PROCESS_FLUSH_FRAMES:
-         /* Flush the frames by updating all transports times */
-         transport_update_time (now, 0);
+       case SESSION_Q_PROCESS_RUN_ON_MAIN:
+         /* Run session queue node on main thread */
+         session_queue_run_on_main (vm);
          break;
        case SESSION_Q_PROCESS_STOP:
+         vlib_node_set_state (vm, session_queue_process_node.index,
+                              VLIB_NODE_STATE_DISABLED);
          timeout = 100000.0;
          break;
        case ~0:
-         /* Timed out. Update time for all transports to trigger all
-          * outstanding retransmits. */
-         transport_update_time (now, 0);
+         /* Timed out. Run on main to ensure all events are handled */
+         session_queue_run_on_main (vm);
          break;
        }
       vec_reset_length (event_data);
@@ -1234,6 +1719,27 @@ VLIB_REGISTER_NODE (session_queue_process_node) =
 };
 /* *INDENT-ON* */
 
+static_always_inline uword
+session_queue_pre_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
+                               vlib_frame_t * frame)
+{
+  session_main_t *sm = &session_main;
+  if (!sm->wrk[0].vpp_event_queue)
+    return 0;
+  node = vlib_node_get_runtime (vm, session_queue_node.index);
+  return session_queue_node_fn (vm, node, frame);
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (session_queue_pre_input_node) =
+{
+  .function = session_queue_pre_input_inline,
+  .type = VLIB_NODE_TYPE_PRE_INPUT,
+  .name = "session-queue-main",
+  .state = VLIB_NODE_STATE_DISABLED,
+};
+/* *INDENT-ON* */
+
 /*
  * fd.io coding-style-patch-verification: ON
  *