session/tcp: improve preallocated segment handling

- add preallocated segment flag
- don't remove pre-allocated segments except if application detaches
- when preallocating fifos in multiple segments, completely fill
  a segment before moving to the next
- detach server application from segment-managers when deleting app
- batch syn/syn-ack/fin (re)transmissions
- loosen up close-wait and time-wait times

Change-Id: I412f53ce601cc83b3acc26aeffd7fa2d52d73b03
Signed-off-by: Florin Coras <fcoras@cisco.com>

4 files changed, 61 insertions, 53 deletions

diff --git a/src/vnet/session/application.c b/src/vnet/session/application.c
index d105119c557..2b789c5f420 100644
--- a/src/vnet/session/application.c
+++ b/src/vnet/session/application.c
@@ -111,6 +111,8 @@ application_del (application_t * app)
   hash_foreach (handle, index, app->listeners_table,
   ({
     vec_add1 (handles, handle);
+    sm = segment_manager_get (index);
+    sm->app_index = SEGMENT_MANAGER_INVALID_APP_INDEX;
   }));
   /* *INDENT-ON* */
 
diff --git a/src/vnet/session/segment_manager.c b/src/vnet/session/segment_manager.c
index c23e4c0237c..48d027553b1 100644
--- a/src/vnet/session/segment_manager.c
+++ b/src/vnet/session/segment_manager.c
@@ -197,27 +197,24 @@ u8
 segment_manager_has_fifos (segment_manager_t * sm)
 {
   svm_fifo_segment_private_t *segment;
-  /* Weird, but handle it */
-  if (vec_len (sm->segment_indices) == 0)
-    return 0;
-  if (vec_len (sm->segment_indices) == 1)
-    {
-      segment = svm_fifo_segment_get_segment (sm->segment_indices[0]);
-      if (svm_fifo_segment_num_fifos (segment) == 0)
-	return 0;
-    }
-  if (CLIB_DEBUG)
+  int i;
+
+  for (i = 0; i < vec_len (sm->segment_indices); i++)
     {
-      svm_fifo_segment_private_t *segment;
-      int i;
-      for (i = 1; i < vec_len (sm->segment_indices); i++)
-	{
-	  segment = svm_fifo_segment_get_segment (sm->segment_indices[i]);
-	  if (!svm_fifo_segment_has_fifos (segment))
-	    clib_warning ("segment has no fifos!");
-	}
+      segment = svm_fifo_segment_get_segment (sm->segment_indices[i]);
+      if (CLIB_DEBUG && i && !svm_fifo_segment_has_fifos (segment)
+	  && !(segment->h->flags & FIFO_SEGMENT_F_IS_PREALLOCATED))
+	clib_warning ("segment %d has no fifos!", sm->segment_indices[i]);
+      if (svm_fifo_segment_has_fifos (segment))
+	return 1;
     }
-  return 1;
+  return 0;
+}
+
+static u8
+segment_manager_app_detached (segment_manager_t * sm)
+{
+  return (sm->app_index == SEGMENT_MANAGER_INVALID_APP_INDEX);
 }
 
 static void
@@ -228,6 +225,13 @@ segment_manager_del_segment (segment_manager_t * sm, u32 segment_index)
   clib_spinlock_lock (&sm->lockp);
   svm_segment_index = sm->segment_indices[segment_index];
   fifo_segment = svm_fifo_segment_get_segment (svm_segment_index);
+  if (!fifo_segment
+      || ((fifo_segment->h->flags & FIFO_SEGMENT_F_IS_PREALLOCATED)
+	  && !segment_manager_app_detached (sm)))
+    {
+      clib_spinlock_unlock (&sm->lockp);
+      return;
+    }
   svm_fifo_segment_delete (fifo_segment);
   vec_del1 (sm->segment_indices, segment_index);
   clib_spinlock_unlock (&sm->lockp);
@@ -288,26 +292,29 @@ segment_manager_del_sessions (segment_manager_t * sm)
  *
  * Since the fifos allocated in the segment keep backpointers to the sessions
  * prior to removing the segment, we call session disconnect. This
- * subsequently propages into transport.
+ * subsequently propagates into transport.
  */
 void
 segment_manager_del (segment_manager_t * sm)
 {
+  int i;
 
-  ASSERT (vec_len (sm->segment_indices) <= 1);
-  if (vec_len (sm->segment_indices))
+  ASSERT (!segment_manager_has_fifos (sm)
+	  && segment_manager_app_detached (sm));
+
+  /* If we have empty preallocated segments that haven't been removed, remove
+   * them now. Apart from that, the first segment in the first segment manager
+   * is not removed when all fifos are removed. It can only be removed when
+   * the manager is explicitly deleted/detached by the app. */
+  for (i = vec_len (sm->segment_indices) - 1; i >= 0; i--)
     {
-      /* The first segment in the first segment manager is not removed when
-       * all fifos are removed. It can only be removed when the manager is
-       * explicitly deleted/detached by the app. */
       if (CLIB_DEBUG)
 	{
-	  svm_fifo_segment_private_t *fifo_segment;
-	  fifo_segment =
-	    svm_fifo_segment_get_segment (sm->segment_indices[0]);
-	  ASSERT (!svm_fifo_segment_has_fifos (fifo_segment));
+	  svm_fifo_segment_private_t *segment;
+	  segment = svm_fifo_segment_get_segment (sm->segment_indices[i]);
+	  ASSERT (!svm_fifo_segment_has_fifos (segment));
 	}
-      segment_manager_del_segment (sm, 0);
+      segment_manager_del_segment (sm, i);
     }
   clib_spinlock_free (&sm->lockp);
   if (CLIB_DEBUG)
@@ -322,8 +329,7 @@ segment_manager_init_del (segment_manager_t * sm)
     segment_manager_del_sessions (sm);
   else
     {
-      ASSERT (!sm->first_is_protected
-	      || sm->app_index == SEGMENT_MANAGER_INVALID_APP_INDEX);
+      ASSERT (!sm->first_is_protected || segment_manager_app_detached (sm));
       segment_manager_del (sm);
     }
 }
@@ -478,7 +484,8 @@ segment_manager_dealloc_fifos (u32 svm_segment_index, svm_fifo_t * rx_fifo,
 	}
 
       /* Remove segment manager if no sessions and detached from app */
-      if (sm->app_index == SEGMENT_MANAGER_INVALID_APP_INDEX && is_first)
+      if (segment_manager_app_detached (sm)
+	  && !segment_manager_has_fifos (sm))
 	segment_manager_del (sm);
     }
 }
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index 792e6612dc1..dc930ce87d3 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -453,7 +453,7 @@ stream_session_connect_notify (transport_connection_t * tc, u8 is_fail)
 						   st);
   if (handle == HALF_OPEN_LOOKUP_INVALID_VALUE)
     {
-      clib_warning ("half-open was removed!");
+      TCP_DBG ("half-open was removed!");
       return -1;
     }
 
@@ -732,6 +732,7 @@ session_send_session_evt_to_thread (u64 session_handle,
 				    u32 thread_index)
 {
   static u16 serial_number = 0;
+  u32 tries = 0;
   session_fifo_event_t evt;
   unix_shared_memory_queue_t *q;
 
@@ -741,21 +742,14 @@ session_send_session_evt_to_thread (u64 session_handle,
   evt.event_id = serial_number++;
 
   q = session_manager_get_vpp_event_queue (thread_index);
-
-  /* Based on request block (or not) for lack of space */
-  if (PREDICT_TRUE (q->cursize < q->maxsize))
+  while (unix_shared_memory_queue_add (q, (u8 *) & evt, 1))
     {
-      if (unix_shared_memory_queue_add (q, (u8 *) & evt,
-					0 /* do wait for mutex */ ))
+      if (tries++ == 3)
 	{
-	  clib_warning ("failed to enqueue evt");
+	  TCP_DBG ("failed to enqueue evt");
+	  break;
 	}
     }
-  else
-    {
-      clib_warning ("queue full");
-      return;
-    }
 }
 
 /**
diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index 09687687189..d015584990e 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -168,15 +168,19 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
       return 0;
     }
 
+  /* Check how much we can pull. */
+  max_dequeue0 = svm_fifo_max_dequeue (s0->server_tx_fifo);
+
   if (peek_data)
     {
-      /* Offset in rx fifo from where to peek data  */
+      /* Offset in rx fifo from where to peek data */
       tx_offset = transport_vft->tx_fifo_offset (tc0);
+      if (PREDICT_FALSE (tx_offset >= max_dequeue0))
+	max_dequeue0 = 0;
+      else
+	max_dequeue0 -= tx_offset;
     }
 
-  /* Check how much we can pull. If buffering, subtract the offset */
-  max_dequeue0 = svm_fifo_max_dequeue (s0->server_tx_fifo) - tx_offset;
-
   /* Nothing to read return */
   if (max_dequeue0 == 0)
     {
@@ -277,6 +281,8 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    {
 	      n_bytes_read = svm_fifo_peek (s0->server_tx_fifo, tx_offset,
 					    len_to_deq0, data0);
+	      if (n_bytes_read <= 0)
+		goto dequeue_fail;
 	      /* Keep track of progress locally, transport is also supposed to
 	       * increment it independently when pushing the header */
 	      tx_offset += n_bytes_read;
@@ -285,11 +291,10 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    {
 	      n_bytes_read = svm_fifo_dequeue_nowait (s0->server_tx_fifo,
 						      len_to_deq0, data0);
+	      if (n_bytes_read <= 0)
+		goto dequeue_fail;
 	    }
 
-	  if (n_bytes_read <= 0)
-	    goto dequeue_fail;
-
 	  b0->current_length = n_bytes_read;
 
 	  left_to_snd0 -= n_bytes_read;
@@ -616,7 +621,7 @@ skip_dequeue:
 	case FIFO_EVENT_APP_TX:
 	  s0 = session_event_get_session (e0, my_thread_index);
 
-	  if (CLIB_DEBUG && !s0)
+	  if (PREDICT_FALSE (!s0))
 	    {
 	      clib_warning ("It's dead, Jim!");
 	      continue;