tcp: better estimate snd space for rxt with no sacks

Type: refactor

Use tcp_available_cc_snd_space instead of sack scoreboard
last_delivered_bytes to estimate available space when retransmitting
with no sack support

Change-Id: I938c637279eaf8c5634c4e97f0633fa2d0054fac
Signed-off-by: Florin Coras <fcoras@cisco.com>

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index a438709..e843edb 100644 (file)
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1549,8 +1549,6 @@ partial_ack:
   else
     {
       tcp_fastrecovery_first_on (tc);
-      /* Reuse last bytes delivered to track total bytes acked */
-      tc->sack_sb.last_bytes_delivered += tc->bytes_acked;
       if (tc->snd_rxt_bytes > tc->bytes_acked)
        tc->snd_rxt_bytes -= tc->bytes_acked;
       else

diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index c9ffd00..77065cd 100644 (file)
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1904,12 +1904,13 @@ tcp_fast_retransmit_no_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
   ASSERT (tcp_in_fastrecovery (tc));
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 0);
 
+  snd_space = tcp_available_cc_snd_space (tc);
+
   if (!tcp_fastrecovery_first (tc))
     goto send_unsent;
 
   /* RFC 6582: [If a partial ack], retransmit the first unacknowledged
    * segment. */
-  snd_space = tc->sack_sb.last_bytes_delivered;
   while (snd_space > 0 && n_segs < burst_size)
     {
       n_written = tcp_prepare_retransmit_segment (wrk, tc, offset,
@@ -1932,7 +1933,6 @@ tcp_fast_retransmit_no_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 send_unsent:
 
   /* RFC 6582: Send a new segment if permitted by the new value of cwnd. */
-  snd_space = tcp_available_cc_snd_space (tc);
   if (snd_space < tc->snd_mss || tc->snd_mss == 0)
     goto done;