commit b3dce89a768aaffa2a830ba6579cd3d9c8cd967a
author Florin Coras <fcoras@cisco.com> Wed Oct 30 09:22:14 2019 -0700
committer Florin Coras <florin.coras@gmail.com> Mon Nov 11 18:45:14 2019 +0000
tree 1b4d603d40f95fe56ef9c77a90468afb2c337240
parent eb284a1f8f10d752285a0a59e75bc54acae50779

tcp: improve lost rxt heuristic

Type: feature

- retransmit first unacked segment if newer retransmitted packets
are acked
- avoid spurious retransmits if recovery ends with sacked bytes

Change-Id: Ic1b56d22e025822edb7609afb136e47440ea6032
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 f403887..7dd88bf 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -1172,8 +1172,14 @@
 always_inline void
 tcp_persist_timer_update (tcp_connection_t * tc)
 {
-  tcp_timer_update (tc, TCP_TIMER_PERSIST,
-		    clib_max (tc->rto * TCP_TO_TIMER_TICK, 1));
+  u32 interval;
+
+  if (seq_leq (tc->snd_una, tc->snd_congestion + tc->burst_acked))
+    interval = 1;
+  else
+    interval = clib_max (tc->rto * TCP_TO_TIMER_TICK, 1);
+
+  tcp_timer_update (tc, TCP_TIMER_PERSIST, interval);
 }
 
 always_inline void