session: move connects to first worker

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I035e3fdbb52eca010ad7b2c20ca2930cb1645978

6 files changed, 54 insertions, 84 deletions

diff --git a/src/vnet/session/application.c b/src/vnet/session/application.c
index 3b2c7cdb35a..ad4d447c543 100644
--- a/src/vnet/session/application.c
+++ b/src/vnet/session/application.c
@@ -1357,7 +1357,7 @@ vnet_connect (vnet_connect_args_t * a)
   app_worker_t *client_wrk;
   application_t *client;
 
-  ASSERT (vlib_thread_is_main_w_barrier ());
+  ASSERT (session_vlib_thread_is_cl_thread ());
 
   if (session_endpoint_is_zero (&a->sep))
     return SESSION_E_INVALID_RMT_IP;
diff --git a/src/vnet/session/application_worker.c b/src/vnet/session/application_worker.c
index 844e78f7fa9..0cb179161b8 100644
--- a/src/vnet/session/application_worker.c
+++ b/src/vnet/session/application_worker.c
@@ -393,7 +393,7 @@ app_worker_add_half_open (app_worker_t *app_wrk, session_handle_t sh)
 {
   session_handle_t *shp;
 
-  ASSERT (vlib_get_thread_index () == 0);
+  ASSERT (session_vlib_thread_is_cl_thread ());
   pool_get (app_wrk->half_open_table, shp);
   *shp = sh;
 
@@ -404,7 +404,7 @@ int
 app_worker_del_half_open (app_worker_t *app_wrk, session_t *s)
 {
   application_t *app = application_get (app_wrk->app_index);
-  ASSERT (vlib_get_thread_index () <= 1);
+  ASSERT (session_vlib_thread_is_cl_thread ());
   pool_put_index (app_wrk->half_open_table, s->ho_index);
   if (app->cb_fns.half_open_cleanup_callback)
     app->cb_fns.half_open_cleanup_callback (s);
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index 91e9ed5451d..eaba80f24e2 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -334,15 +334,15 @@ void
 session_half_open_delete_notify (transport_connection_t *tc)
 {
   /* Notification from ctrl thread accepted without rpc */
-  if (!tc->thread_index)
+  if (tc->thread_index == transport_cl_thread ())
     {
       session_half_open_free (ho_session_get (tc->s_index));
     }
   else
     {
       void *args = uword_to_pointer ((uword) tc->s_index, void *);
-      session_send_rpc_evt_to_thread_force (0, session_half_open_free_rpc,
-					    args);
+      session_send_rpc_evt_to_thread_force (transport_cl_thread (),
+					    session_half_open_free_rpc, args);
     }
 }
 
diff --git a/src/vnet/session/session.h b/src/vnet/session/session.h
index 16000e62fa8..b8cc1c383c9 100644
--- a/src/vnet/session/session.h
+++ b/src/vnet/session/session.h
@@ -157,9 +157,6 @@ typedef struct session_worker_
   /** Flag that is set if main thread signaled to handle connects */
   u32 n_pending_connects;
 
-  /** Main thread loops in poll mode without a connect */
-  u32 no_connect_loops;
-
   /** List head for first worker evts pending handling on main */
   clib_llist_index_t evts_pending_main;
 
@@ -212,7 +209,9 @@ typedef struct session_main_
    * Trade memory for speed, for now */
   u32 *session_type_to_next;
 
-  /** Thread for cl and ho that rely on cl allocs */
+  /** Thread used for allocating active open connections, i.e., half-opens
+   * for transports like tcp, and sessions that will be migrated for cl
+   * transports like udp. If vpp has workers, this will be first worker. */
   u32 transport_cl_thread;
 
   transport_proto_t last_transport_proto_type;
@@ -616,6 +615,13 @@ transport_cl_thread (void)
   return session_main.transport_cl_thread;
 }
 
+always_inline u32
+session_vlib_thread_is_cl_thread (void)
+{
+  return (vlib_get_thread_index () == transport_cl_thread () ||
+	  vlib_thread_is_main_w_barrier ());
+}
+
 /*
  * Listen sessions
  */
@@ -668,29 +674,17 @@ always_inline session_t *
 ho_session_alloc (void)
 {
   session_t *s;
-  ASSERT (vlib_get_thread_index () == 0);
-  s = session_alloc (0);
+  ASSERT (session_vlib_thread_is_cl_thread ());
+  s = session_alloc (transport_cl_thread ());
   s->session_state = SESSION_STATE_CONNECTING;
   s->flags |= SESSION_F_HALF_OPEN;
-  /* Not ideal. Half-opens are only allocated from main with worker barrier
-   * but can be cleaned up, i.e., session_half_open_free, from main without
-   * a barrier. In debug images, the free_bitmap can grow while workers peek
-   * the sessions pool, e.g., session_half_open_migrate_notify, and as a
-   * result crash while validating the session. To avoid this, grow the bitmap
-   * now. */
-  if (CLIB_DEBUG)
-    {
-      session_t *sp = session_main.wrk[0].sessions;
-      clib_bitmap_validate (pool_header (sp)->free_bitmap,
-			    s->session_index + 1);
-    }
   return s;
 }
 
 always_inline session_t *
 ho_session_get (u32 ho_index)
 {
-  return session_get (ho_index, 0 /* half-open thread */);
+  return session_get (ho_index, transport_cl_thread ());
 }
 
 always_inline void
diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index 8f6503d2806..be00925bb00 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -224,23 +224,20 @@ static void
 session_mq_handle_connects_rpc (void *arg)
 {
   u32 max_connects = 32, n_connects = 0;
-  vlib_main_t *vm = vlib_get_main ();
   session_evt_elt_t *he, *elt, *next;
-  session_worker_t *fwrk, *wrk;
+  session_worker_t *fwrk;
 
-  ASSERT (vlib_get_thread_index () == 0);
+  ASSERT (session_vlib_thread_is_cl_thread ());
 
   /* Pending connects on linked list pertaining to first worker */
-  fwrk = session_main_get_worker (1);
+  fwrk = session_main_get_worker (transport_cl_thread ());
   if (!fwrk->n_pending_connects)
-    goto update_state;
-
-  vlib_worker_thread_barrier_sync (vm);
+    return;
 
   he = clib_llist_elt (fwrk->event_elts, fwrk->pending_connects);
   elt = clib_llist_next (fwrk->event_elts, evt_list, he);
 
-  /* Avoid holding the barrier for too long */
+  /* Avoid holding the worker for too long */
   while (n_connects < max_connects && elt != he)
     {
       next = clib_llist_next (fwrk->event_elts, evt_list, elt);
@@ -254,45 +251,10 @@ session_mq_handle_connects_rpc (void *arg)
 
   /* Decrement with worker barrier */
   fwrk->n_pending_connects -= n_connects;
-
-  vlib_worker_thread_barrier_release (vm);
-
-update_state:
-
-  /* Switch worker to poll mode if it was in interrupt mode and had work or
-   * back to interrupt if threshold of loops without a connect is passed.
-   * While in poll mode, reprogram connects rpc */
-  wrk = session_main_get_worker (0);
-  if (wrk->state != SESSION_WRK_POLLING)
-    {
-      if (n_connects)
-	{
-	  session_wrk_set_state (wrk, SESSION_WRK_POLLING);
-	  vlib_node_set_state (vm, session_queue_node.index,
-			       VLIB_NODE_STATE_POLLING);
-	  wrk->no_connect_loops = 0;
-	}
-    }
-  else
-    {
-      if (!n_connects)
-	{
-	  if (++wrk->no_connect_loops > 1e5)
-	    {
-	      session_wrk_set_state (wrk, SESSION_WRK_INTERRUPT);
-	      vlib_node_set_state (vm, session_queue_node.index,
-				   VLIB_NODE_STATE_INTERRUPT);
-	    }
-	}
-      else
-	wrk->no_connect_loops = 0;
-    }
-
-  if (wrk->state == SESSION_WRK_POLLING)
+  if (fwrk->n_pending_connects > 0)
     {
-      elt = session_evt_alloc_ctrl (wrk);
-      elt->evt.event_type = SESSION_CTRL_EVT_RPC;
-      elt->evt.rpc_args.fp = session_mq_handle_connects_rpc;
+      session_send_rpc_evt_to_thread_force (fwrk->vm->thread_index,
+					    session_mq_handle_connects_rpc, 0);
     }
 }
 
@@ -302,20 +264,28 @@ session_mq_connect_handler (session_worker_t *wrk, session_evt_elt_t *elt)
   u32 thread_index = wrk - session_main.wrk;
   session_evt_elt_t *he;
 
-  /* No workers, so just deal with the connect now */
-  if (PREDICT_FALSE (!thread_index))
+  if (PREDICT_FALSE (thread_index > transport_cl_thread ()))
     {
-      session_mq_connect_one (session_evt_ctrl_data (wrk, elt));
+      clib_warning ("Connect on wrong thread. Dropping");
       return;
     }
 
-  if (PREDICT_FALSE (thread_index != 1))
+  /* If on worker, check if main has any pending messages. Avoids reordering
+   * with other control messages that need to be handled by main
+   */
+  if (thread_index)
     {
-      clib_warning ("Connect on wrong thread. Dropping");
-      return;
+      he = clib_llist_elt (wrk->event_elts, wrk->evts_pending_main);
+
+      /* Events pending on main, postpone to avoid reordering */
+      if (!clib_llist_is_empty (wrk->event_elts, evt_list, he))
+	{
+	  clib_llist_add_tail (wrk->event_elts, evt_list, elt, he);
+	  return;
+	}
     }
 
-  /* Add to pending list to be handled by main thread */
+  /* Add to pending list to be handled by first worker */
   he = clib_llist_elt (wrk->event_elts, wrk->pending_connects);
   clib_llist_add_tail (wrk->event_elts, evt_list, elt, he);
 
@@ -323,9 +293,8 @@ session_mq_connect_handler (session_worker_t *wrk, session_evt_elt_t *elt)
   wrk->n_pending_connects += 1;
   if (wrk->n_pending_connects == 1)
     {
-      vlib_node_set_interrupt_pending (vlib_get_main_by_index (0),
-				       session_queue_node.index);
-      session_send_rpc_evt_to_thread (0, session_mq_handle_connects_rpc, 0);
+      session_send_rpc_evt_to_thread_force (thread_index,
+					    session_mq_handle_connects_rpc, 0);
     }
 }
 
@@ -812,6 +781,9 @@ session_wrk_handle_evts_main_rpc (void *args)
 	case SESSION_CTRL_EVT_ACCEPTED_REPLY:
 	  session_mq_accepted_reply_handler (fwrk, elt);
 	  break;
+	case SESSION_CTRL_EVT_CONNECT:
+	  session_mq_connect_handler (fwrk, elt);
+	  break;
 	default:
 	  clib_warning ("unhandled %u", elt->evt.event_type);
 	  ALWAYS_ASSERT (0);
@@ -820,8 +792,11 @@ session_wrk_handle_evts_main_rpc (void *args)
 
       /* Regrab element in case pool moved */
       elt = clib_llist_elt (fwrk->event_elts, ei);
-      session_evt_ctrl_data_free (fwrk, elt);
-      clib_llist_put (fwrk->event_elts, elt);
+      if (!clib_llist_elt_is_linked (elt, evt_list))
+	{
+	  session_evt_ctrl_data_free (fwrk, elt);
+	  clib_llist_put (fwrk->event_elts, elt);
+	}
       ei = next_ei;
     }
 
diff --git a/src/vnet/session/transport.c b/src/vnet/session/transport.c
index b13370bcffd..8554c730bda 100644
--- a/src/vnet/session/transport.c
+++ b/src/vnet/session/transport.c
@@ -486,7 +486,8 @@ transport_program_endpoint_cleanup (u32 lepi)
   clib_spinlock_unlock (&tm->local_endpoints_lock);
 
   if (flush_fl)
-    session_send_rpc_evt_to_thread_force (0, transport_cleanup_freelist, 0);
+    session_send_rpc_evt_to_thread_force (transport_cl_thread (),
+					  transport_cleanup_freelist, 0);
 }
 
 int