commit cb711a4ec908b89edc9da29d3c2e093dab85fbbf
author Florin Coras <fcoras@cisco.com> Wed Oct 16 19:28:17 2019 -0700
committer Dave Barach <openvpp@barachs.net> Thu Oct 17 18:42:18 2019 +0000
tree f1243df614041ccd384ff88e078ab490f668591c
parent ec44e263728e6795f77e1d16d6c07eeb093b4f34

tcp: avoid sending acks when data available

Type: fix

Change-Id: I02e2cb2d349f9ddb2bfed040a08ca448f379d565
Signed-off-by: Florin Coras <fcoras@cisco.com>

src/vnet/tcp/tcp.h

diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 097a147..825099a 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -786,6 +786,7 @@
 void tcp_send_syn (tcp_connection_t * tc);
 void tcp_send_synack (tcp_connection_t * tc);
 void tcp_send_fin (tcp_connection_t * tc);
+void tcp_send_ack (tcp_connection_t * tc);
 void tcp_update_burst_snd_vars (tcp_connection_t * tc);
 void tcp_update_rto (tcp_connection_t * tc);
 void tcp_flush_frame_to_output (tcp_worker_ctx_t * wrk, u8 is_ip4);

src/vnet/tcp/tcp_input.c

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 22222fb..10f96fa 100755
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1681,6 +1681,7 @@
 
   /* Account for the FIN and send ack */
   tc->rcv_nxt += 1;
+  tc->flags |= TCP_CONN_FINRCVD;
   tcp_program_ack (tc);
   /* Enter CLOSE-WAIT and notify session. To avoid lingering
    * in CLOSE-WAIT, set timer (reuse WAITCLOSE). */
@@ -2593,7 +2594,9 @@
 	}
       else
 	{
-	  tcp_program_ack (new_tc0);
+	  /* Send ack now instead of programming it because connection was
+	   * just established and it's not optional. */
+	  tcp_send_ack (new_tc0);
 	}
 
     drop:

src/vnet/tcp/tcp_output.c

diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 08099ff..6ba0ee2 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -518,7 +518,6 @@
   return checksum;
 }
 
-
 /**
  * Prepare ACK
  */
@@ -1086,6 +1085,10 @@
       return;
     }
 
+  /* If we have non-dupacks programmed, no need to send them */
+  if ((tc->flags & TCP_CONN_SNDACK) && !tc->pending_dupacks)
+    tc->flags &= ~TCP_CONN_SNDACK;
+
   tcp_retransmit_timer_force_update (tc);
   b = vlib_get_buffer (vm, bi);
   tcp_init_buffer (vm, b);
@@ -1165,7 +1168,6 @@
   tc->bytes_out += data_len;
   tc->data_segs_out += 1;
 
-
   th->checksum = tcp_compute_checksum (tc, b);
 
   TCP_EVT (TCP_EVT_PKTIZE, tc);
@@ -1883,6 +1885,13 @@
   return (tx_adv_sack > (tc->snd_una - tc->prr_start) * rr);
 }
 
+static inline u8
+tcp_max_tx_deq (tcp_connection_t * tc)
+{
+  return (transport_max_tx_dequeue (&tc->connection)
+	  - (tc->snd_nxt - tc->snd_una));
+}
+
 #define scoreboard_rescue_rxt_valid(_sb, _tc)			\
     (seq_geq (_sb->rescue_rxt, _tc->snd_una) 			\
 	&& seq_leq (_sb->rescue_rxt, _tc->snd_congestion))
@@ -2145,8 +2154,13 @@
 
   if (!tc->pending_dupacks)
     {
-      tcp_send_ack (tc);
-      return 1;
+      if (tcp_in_cong_recovery (tc) || !tcp_max_tx_deq (tc)
+	  || tc->state != TCP_STATE_ESTABLISHED)
+	{
+	  tcp_send_ack (tc);
+	  return 1;
+	}
+      return 0;
     }
 
   /* If we're supposed to send dupacks but have no ooo data
@@ -2154,6 +2168,7 @@
   if (!vec_len (tc->snd_sacks))
     {
       tcp_send_ack (tc);
+      tc->pending_dupacks = 0;
       return 1;
     }