session tls: improve app transports tx scheduling

Type: improvement

- allow apps to request rescheduling of tx events via
SESSION_F_CUSTOM_TX flag
- limit max burst per session custom tx dispatch

In tls
- use the new infra to reschedule tx events
- use max burst bytes as upper limit to number of bytes to be encrypted

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I544a5a3337af7ebdff3406b776adf30cf96ebf3c

4 files changed, 37 insertions, 18 deletions

diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index c2a6ec921af..30eca1e6577 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -1066,15 +1066,37 @@ session_tx_fifo_dequeue_and_snd (session_worker_t * wrk,
 int
 session_tx_fifo_dequeue_internal (session_worker_t * wrk,
 				  vlib_node_runtime_t * node,
-				  session_evt_elt_t * e, int *n_tx_packets)
+				  session_evt_elt_t * elt, int *n_tx_packets)
 {
   session_t *s = wrk->ctx.s;
+  u32 n_packets, max_pkts;
 
   if (PREDICT_FALSE (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
     return 0;
-  svm_fifo_unset_event (s->tx_fifo);
-  return transport_custom_tx (session_get_transport_proto (s), s,
-			      VLIB_FRAME_SIZE - *n_tx_packets);
+
+  /* Clear custom-tx flag used to request reschedule for tx */
+  s->flags &= ~SESSION_F_CUSTOM_TX;
+
+  max_pkts = clib_min (VLIB_FRAME_SIZE - *n_tx_packets,
+		       TRANSPORT_PACER_MAX_BURST_PKTS);
+  n_packets = transport_custom_tx (session_get_transport_proto (s), s,
+				   max_pkts);
+  *n_tx_packets -= n_packets;
+
+  if (svm_fifo_max_dequeue_cons (s->tx_fifo)
+      || (s->flags & SESSION_F_CUSTOM_TX))
+    {
+      session_evt_add_old (wrk, elt);
+    }
+  else
+    {
+      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);
+    }
+
+  return n_packets;
 }
 
 always_inline session_t *
diff --git a/src/vnet/session/transport.h b/src/vnet/session/transport.h
index 53a0dd6c14e..6dc6984cdf4 100644
--- a/src/vnet/session/transport.h
+++ b/src/vnet/session/transport.h
@@ -22,6 +22,7 @@
 #define TRANSPORT_PACER_MIN_MSS 	1460
 #define TRANSPORT_PACER_MIN_BURST 	TRANSPORT_PACER_MIN_MSS
 #define TRANSPORT_PACER_MAX_BURST	(43 * TRANSPORT_PACER_MIN_MSS)
+#define TRANSPORT_PACER_MAX_BURST_PKTS	43
 #define TRANSPORT_PACER_MIN_IDLE	100
 #define TRANSPORT_PACER_IDLE_FACTOR	0.05
 
diff --git a/src/vnet/tls/tls.c b/src/vnet/tls/tls.c
index 7a172b88928..d0552dc6f3b 100644
--- a/src/vnet/tls/tls.c
+++ b/src/vnet/tls/tls.c
@@ -74,15 +74,6 @@ tls_add_vpp_q_tx_evt (session_t * s)
   return 0;
 }
 
-int
-tls_add_vpp_q_builtin_tx_evt (session_t * s)
-{
-  if (svm_fifo_set_event (s->tx_fifo))
-    session_send_io_evt_to_thread_custom (s, s->thread_index,
-					  SESSION_IO_EVT_BUILTIN_TX);
-  return 0;
-}
-
 static inline int
 tls_add_app_q_evt (app_worker_t * app, session_t * app_session)
 {
@@ -316,9 +307,14 @@ tls_ctx_init_client (tls_ctx_t * ctx)
 }
 
 static inline int
-tls_ctx_write (tls_ctx_t * ctx, session_t * app_session)
+tls_ctx_write (tls_ctx_t * ctx, session_t * app_session, u32 max_burst_size)
 {
-  return tls_vfts[ctx->tls_ctx_engine].ctx_write (ctx, app_session);
+  u32 max_write, n_wrote;
+
+  max_write = max_burst_size * TRANSPORT_PACER_MIN_MSS;
+  n_wrote = tls_vfts[ctx->tls_ctx_engine].ctx_write (ctx, app_session,
+						     max_write);
+  return n_wrote > 0 ? clib_max (n_wrote / TRANSPORT_PACER_MIN_MSS, 1) : 0;
 }
 
 static inline int
@@ -726,7 +722,7 @@ tls_custom_tx_callback (void *session, u32 max_burst_size)
     return 0;
 
   ctx = tls_ctx_get (app_session->connection_index);
-  tls_ctx_write (ctx, app_session);
+  tls_ctx_write (ctx, app_session, max_burst_size);
   return 0;
 }
 
@@ -890,7 +886,7 @@ tls_init (vlib_main_t * vm)
 {
   u32 add_segment_size = 256 << 20, first_seg_size = 32 << 20;
   vlib_thread_main_t *vtm = vlib_get_thread_main ();
-  u32 num_threads, fifo_size = 128 << 10;
+  u32 num_threads, fifo_size = 128 << 12;
   vnet_app_attach_args_t _a, *a = &_a;
   u64 options[APP_OPTIONS_N_OPTIONS];
   tls_main_t *tm = &tls_main;
diff --git a/src/vnet/tls/tls.h b/src/vnet/tls/tls.h
index 1281e3d62c9..2d09b291aa7 100644
--- a/src/vnet/tls/tls.h
+++ b/src/vnet/tls/tls.h
@@ -110,7 +110,7 @@ typedef struct tls_engine_vft_
   int (*ctx_init_client) (tls_ctx_t * ctx);
   int (*ctx_init_server) (tls_ctx_t * ctx);
   int (*ctx_read) (tls_ctx_t * ctx, session_t * tls_session);
-  int (*ctx_write) (tls_ctx_t * ctx, session_t * app_session);
+  int (*ctx_write) (tls_ctx_t * ctx, session_t * app_session, u32 max_write);
     u8 (*ctx_handshake_is_over) (tls_ctx_t * ctx);
   int (*ctx_start_listen) (tls_ctx_t * ctx);
   int (*ctx_stop_listen) (tls_ctx_t * ctx);