tcp: force deschedule if no send space available

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Iae9f118f710153b6c0e390265039db7434e67ed8

4 files changed, 13 insertions, 12 deletions

diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index 15d949c76b5..8b268c00b64 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -130,7 +130,8 @@ session_add_self_custom_tx_evt (transport_connection_t * tc, u8 has_prio)
   if (!(s->flags & SESSION_F_CUSTOM_TX))
     {
       s->flags |= SESSION_F_CUSTOM_TX;
-      if (svm_fifo_set_event (s->tx_fifo))
+      if (svm_fifo_set_event (s->tx_fifo)
+	  || transport_connection_is_descheduled (tc))
 	{
 	  session_worker_t *wrk;
 	  session_evt_elt_t *elt;
@@ -141,6 +142,7 @@ session_add_self_custom_tx_evt (transport_connection_t * tc, u8 has_prio)
 	    elt = session_evt_alloc_old (wrk);
 	  elt->evt.session_index = tc->s_index;
 	  elt->evt.event_type = SESSION_IO_EVT_TX;
+	  tc->flags &= ~TRANSPORT_CONNECTION_F_DESCHED;
 	}
     }
 }
diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index b1c2428874e..b5f4321c9a8 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -872,7 +872,7 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
 	  (ctx->s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
 	return SESSION_TX_OK;
       max_burst -= n_custom_tx;
-      if (!max_burst)
+      if (!max_burst || (ctx->s->flags & SESSION_F_CUSTOM_TX))
 	{
 	  session_evt_add_old (wrk, elt);
 	  return SESSION_TX_OK;
@@ -883,18 +883,18 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
 
   if (!ctx->sp.snd_space)
     {
-      /* This flow queue is "empty" so it should be re-evaluated before
-       * the ones that have data to send. */
-      if (PREDICT_TRUE (!ctx->sp.flags))
-	session_evt_add_head_old (wrk, elt);
+      /* 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);
-      /* If the deschedule flag was set, remove session from scheduler.
-       * Transport is responsible for rescheduling this session. */
+      /* This flow queue is "empty" so it should be re-evaluated before
+       * the ones that have data to send. */
       else
-	transport_connection_deschedule (ctx->tc);
+	session_evt_add_head_old (wrk, elt);
 
       return SESSION_TX_NO_DATA;
     }
diff --git a/src/vnet/session/transport.c b/src/vnet/session/transport.c
index e27aaf3ff6b..16f4f02cbe3 100644
--- a/src/vnet/session/transport.c
+++ b/src/vnet/session/transport.c
@@ -725,6 +725,7 @@ void
 transport_connection_reschedule (transport_connection_t * tc)
 {
   tc->flags &= ~TRANSPORT_CONNECTION_F_DESCHED;
+  transport_connection_tx_pacer_reset_bucket (tc, TRANSPORT_PACER_MIN_BURST);
   if (transport_max_tx_dequeue (tc))
     sesssion_reschedule_tx (tc);
   else
diff --git a/src/vnet/session/transport.h b/src/vnet/session/transport.h
index b2be990947c..3c4e15a9a6b 100644
--- a/src/vnet/session/transport.h
+++ b/src/vnet/session/transport.h
@@ -184,9 +184,7 @@ transport_connection_snd_params (transport_connection_t * tc,
 static inline u8
 transport_connection_is_descheduled (transport_connection_t * tc)
 {
-  if (tc->flags & TRANSPORT_CONNECTION_F_DESCHED)
-    return 1;
-  return 0;
+  return ((tc->flags & TRANSPORT_CONNECTION_F_DESCHED) ? 1 : 0);
 }
 
 static inline void