tcp: avoid fr segments less than mss if possible

Type: improvement

Change-Id: I958e059384db3c13a29f64be96877f57617bbae2
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index e232ed4..78148cd 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1810,7 +1810,11 @@
 	  break;
 	}
 
-      max_bytes = clib_min (hole->end - sb->high_rxt, snd_space);
+      max_bytes = hole->end - sb->high_rxt;
+      /* Avoid retransmitting segment less than mss if possible */
+      if (snd_space < tc->snd_mss && max_bytes > snd_space)
+	break;
+      max_bytes = clib_min (max_bytes, snd_space);
       max_bytes = snd_limited ? clib_min (max_bytes, tc->snd_mss) : max_bytes;
       if (max_bytes == 0)
 	break;