session: measure dispatch period only if under load

Also reset pacer on tcp retransmit timeout

Change-Id: I5a9edee4c00d1d169248d79587a9b10437c2bd87
Signed-off-by: Florin Coras <fcoras@cisco.com>

4 files changed, 22 insertions, 11 deletions

diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index 1726355f0e3..ba427b76b1a 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -1153,7 +1153,7 @@ const static transport_proto_vft_t tcp_proto = {
 /* *INDENT-ON* */
 
 void
-tcp_update_pacer (tcp_connection_t * tc)
+tcp_connection_tx_pacer_update (tcp_connection_t * tc)
 {
   f64 srtt;
 
@@ -1165,6 +1165,17 @@ tcp_update_pacer (tcp_connection_t * tc)
 					((f64) tc->cwnd) / srtt);
 }
 
+void
+tcp_connection_tx_pacer_reset (tcp_connection_t * tc, u32 window,
+			       u32 start_bucket)
+{
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  u32 byte_rate = window / ((f64) TCP_TICK * tc->srtt);
+  u64 last_time = wrk->vm->clib_time.last_cpu_time;
+  transport_connection_tx_pacer_reset (&tc->connection, byte_rate,
+				       start_bucket, last_time);
+}
+
 static void
 tcp_timer_keep_handler (u32 conn_index)
 {
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 71af461aca3..bd5e4f71bdb 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -735,14 +735,16 @@ void tcp_connection_timers_init (tcp_connection_t * tc);
 void tcp_connection_timers_reset (tcp_connection_t * tc);
 void tcp_init_snd_vars (tcp_connection_t * tc);
 void tcp_connection_init_vars (tcp_connection_t * tc);
-void tcp_update_pacer (tcp_connection_t * tc);
+void tcp_connection_tx_pacer_update (tcp_connection_t * tc);
+void tcp_connection_tx_pacer_reset (tcp_connection_t * tc, u32 window,
+				    u32 start_bucket);
 
 always_inline void
 tcp_cc_rcv_ack (tcp_connection_t * tc)
 {
   tc->cc_algo->rcv_ack (tc);
   tc->tsecr_last_ack = tc->rcv_opts.tsecr;
-  tcp_update_pacer (tc);
+  tcp_connection_tx_pacer_update (tc);
 }
 
 always_inline void
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index af13c5f8215..fb2f1ddc9ef 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1085,10 +1085,6 @@ tcp_cc_fastrecovery_exit (tcp_connection_t * tc)
   tcp_fastrecovery_1_smss_off (tc);
   tcp_fastrecovery_first_off (tc);
 
-  /* Update pacer because our cwnd changed. Also makes sure
-   * that we recompute the max burst size */
-  tcp_update_pacer (tc);
-
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 3);
 }
 
@@ -1290,7 +1286,8 @@ tcp_cc_handle_event (tcp_connection_t * tc, u32 is_dack)
 	}
       else if (tcp_should_fastrecover (tc))
 	{
-	  u32 byte_rate;
+	  u32 pacer_wnd;
+
 	  ASSERT (!tcp_in_fastrecovery (tc));
 
 	  /* Heuristic to catch potential late dupacks
@@ -1319,8 +1316,9 @@ tcp_cc_handle_event (tcp_connection_t * tc, u32 is_dack)
 	      tc->cwnd = tc->ssthresh + 3 * tc->snd_mss;
 	    }
 
-	  byte_rate = (0.3 * tc->cwnd) / ((f64) TCP_TICK * tc->srtt);
-	  transport_connection_tx_pacer_init (&tc->connection, byte_rate, 0);
+	  pacer_wnd = clib_max (0.1 * tc->cwnd, 2 * tc->snd_mss);
+	  tcp_connection_tx_pacer_reset (tc, pacer_wnd,
+					 0 /* start bucket */ );
 	  tcp_program_fastretransmit (tcp_get_worker (tc->c_thread_index),
 				      tc);
 	  return;
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index c315c031c97..c135a311fb5 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1406,7 +1406,7 @@ tcp_rxt_timeout_cc (tcp_connection_t * tc)
   tc->snd_congestion = tc->snd_una_max;
   tc->rtt_ts = 0;
   tc->cwnd_acc_bytes = 0;
-
+  tcp_connection_tx_pacer_reset (tc, tc->cwnd, 2 * tc->snd_mss);
   tcp_recovery_on (tc);
 }