session: async rx event notifications

Move from synchronous flushing of io and ctrl events from transports to
applications to an async model via a new session_input input node that
runs in interrupt mode. Events are coalesced per application worker.

On the one hand, this helps by minimizing message queue locking churn.
And on the other, it opens the possibility for further optimizations of
event message generation, obviates need for rx rescheduling rpcs and is
a first step towards a fully async data/io rx path.

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Id6bebcb65fc9feef8aa02ddf1af6d9ba6f6745ce

1 files changed, 6 insertions, 13 deletions

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index f0d039fbbb8..3d8afaaba3d 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1394,11 +1394,10 @@ always_inline uword
 tcp46_established_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 			  vlib_frame_t * frame, int is_ip4)
 {
-  u32 thread_index = vm->thread_index, errors = 0;
+  u32 thread_index = vm->thread_index, n_left_from, *from;
   tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
   u16 err_counters[TCP_N_ERROR] = { 0 };
-  u32 n_left_from, *from;
 
   if (node->flags & VLIB_NODE_FLAG_TRACE)
     tcp_established_trace_frame (vm, node, frame, is_ip4);
@@ -1462,9 +1461,7 @@ tcp46_established_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
       b += 1;
     }
 
-  errors = session_main_flush_enqueue_events (TRANSPORT_PROTO_TCP,
-					      thread_index);
-  err_counters[TCP_ERROR_MSG_QUEUE_FULL] = errors;
+  session_main_flush_enqueue_events (TRANSPORT_PROTO_TCP, thread_index);
   tcp_store_err_counters (established, err_counters);
   tcp_handle_postponed_dequeues (wrk);
   tcp_handle_disconnects (wrk);
@@ -1746,7 +1743,7 @@ always_inline uword
 tcp46_syn_sent_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 		       vlib_frame_t *frame, int is_ip4)
 {
-  u32 n_left_from, *from, thread_index = vm->thread_index, errors = 0;
+  u32 n_left_from, *from, thread_index = vm->thread_index;
   tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
 
@@ -1981,9 +1978,7 @@ tcp46_syn_sent_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
       tcp_inc_counter (syn_sent, error, 1);
     }
 
-  errors =
-    session_main_flush_enqueue_events (TRANSPORT_PROTO_TCP, thread_index);
-  tcp_inc_counter (syn_sent, TCP_ERROR_MSG_QUEUE_FULL, errors);
+  session_main_flush_enqueue_events (TRANSPORT_PROTO_TCP, thread_index);
   vlib_buffer_free (vm, from, frame->n_vectors);
   tcp_handle_disconnects (wrk);
 
@@ -2058,7 +2053,7 @@ always_inline uword
 tcp46_rcv_process_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 			  vlib_frame_t *frame, int is_ip4)
 {
-  u32 thread_index = vm->thread_index, errors, n_left_from, *from, max_deq;
+  u32 thread_index = vm->thread_index, n_left_from, *from, max_deq;
   tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
 
@@ -2431,9 +2426,7 @@ tcp46_rcv_process_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
       tcp_inc_counter (rcv_process, error, 1);
     }
 
-  errors = session_main_flush_enqueue_events (TRANSPORT_PROTO_TCP,
-					      thread_index);
-  tcp_inc_counter (rcv_process, TCP_ERROR_MSG_QUEUE_FULL, errors);
+  session_main_flush_enqueue_events (TRANSPORT_PROTO_TCP, thread_index);
   tcp_handle_postponed_dequeues (wrk);
   tcp_handle_disconnects (wrk);
   vlib_buffer_free (vm, from, frame->n_vectors);