tcp: compute snd time for rate sample

Type: feature

Change-Id: I6bd675dc28dbc34293e895911efe986844c0564f
Signed-off-by: Florin Coras <fcoras@cisco.com>

3 files changed, 28 insertions, 29 deletions

diff --git a/src/plugins/unittest/tcp_test.c b/src/plugins/unittest/tcp_test.c
index 42fa423bfae..f6a389c5c88 100644
--- a/src/plugins/unittest/tcp_test.c
+++ b/src/plugins/unittest/tcp_test.c
@@ -820,14 +820,6 @@ tbt_seq_lt (u32 a, u32 b)
   return seq_lt (a, b);
 }
 
-static inline int
-approx_equal (u32 a, u32 b)
-{
-  if (b > 0.99 * a && b < 1.01 * a)
-    return 1;
-  return 0;
-}
-
 static int
 tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
 {
@@ -894,9 +886,8 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
   TCP_TEST (rs->interval_time == 1, "ack time should be 1");
   TCP_TEST (rs->delivered == burst, "delivered should be 100");
   TCP_TEST (rs->prior_delivered == 0, "sample delivered should be 0");
-  TCP_TEST (approx_equal (rate, rs->tx_rate), "rate should be %u is %u", rate,
-	    rs->tx_rate);
   TCP_TEST (!(rs->flags & TCP_BTS_IS_RXT), "not retransmitted");
+  TCP_TEST (tc->first_tx_time == 1, "first_tx_time %u", tc->first_tx_time);
 
   /* 3) track second burst at time 2 */
   tcp_bt_track_tx (tc);
@@ -934,10 +925,9 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
   TCP_TEST (rs->interval_time == 2, "ack time should be 2");
   TCP_TEST (rs->delivered == 2 * burst, "delivered should be 200");
   TCP_TEST (rs->prior_delivered == burst, "delivered should be 100");
-  TCP_TEST (approx_equal (rate, rs->tx_rate), "rate should be %u is %u", rate,
-	    rs->tx_rate);
   TCP_TEST (!(rs->flags & TCP_BTS_IS_RXT), "not retransmitted");
   TCP_TEST (!(bts->flags & TCP_BTS_IS_APP_LIMITED), "not app limited");
+  TCP_TEST (tc->first_tx_time == 2, "first_tx_time %u", tc->first_tx_time);
 
   /*
    * Track retransmissions
@@ -947,7 +937,7 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
 
   snd_una = tc->snd_una;
 
-  /* 1) track first burst a time 4 */
+  /* 1) track first burst at time 4 */
   tcp_bt_track_tx (tc);
   tc->snd_nxt += burst;
 
@@ -1003,10 +993,11 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
   TCP_TEST (rs->delivered == 30, "delivered should be 30");
   TCP_TEST (rs->prior_delivered == 3 * burst,
 	    "sample delivered should be %u", 3 * burst);
-  TCP_TEST (approx_equal (rate, rs->tx_rate), "rate should be %u is %u", rate,
-	    rs->tx_rate);
   TCP_TEST (!(rs->flags & TCP_BTS_IS_RXT), "not retransmitted");
   TCP_TEST (!(rs->flags & TCP_BTS_IS_APP_LIMITED), "not app limited");
+  /* All 3 samples have the same delivered number of bytes. The first
+   * sets the first tx time */
+  TCP_TEST (tc->first_tx_time == 4, "first_tx_time %u", tc->first_tx_time);
 
   /* 6) Retransmit and track at time 9
    *
@@ -1079,20 +1070,22 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
   TCP_TEST (tc->delivered_time == 10, "delivered time should be 10");
   TCP_TEST (tc->delivered == 5 * burst + 40, "delivered should be %u is %u",
 	    5 * burst + 40, tc->delivered);
-  /* A rxt was acked and delivered time for it is 8 (last ack time) */
-  TCP_TEST (rs->interval_time == 2, "ack time should be 2 is %.2f",
+  /* A rxt was acked and delivered time for it is 8 (last ack time) so
+   * ack_time is 2 (8 - 10). However, first_tx_time for rxt was 4 and rxt
+   * time 9. Therefore snd_time is 5 (9 - 4)*/
+  TCP_TEST (rs->interval_time == 5, "ack time should be 5 is %.2f",
 	    rs->interval_time);
   /* delivered_now - delivered_rxt ~ 5 * burst + 40 - 3 * burst - 30 */
   TCP_TEST (rs->delivered == 2 * burst + 10, "delivered should be 210 is %u",
 	    rs->delivered);
   TCP_TEST (rs->prior_delivered == 3 * burst + 30,
 	    "sample delivered should be %u", 3 * burst + 30);
-  TCP_TEST (approx_equal (rate, rs->tx_rate), "rate should be %u is %u", rate,
-	    rs->tx_rate);
   TCP_TEST (rs->flags & TCP_BTS_IS_RXT, "is retransmitted");
   /* Sample is app limited because of the retransmits */
   TCP_TEST (rs->flags & TCP_BTS_IS_APP_LIMITED, "is app limited");
   TCP_TEST (tc->app_limited, "app limited should be set");
+  TCP_TEST (tc->first_tx_time == 9, "first_tx_time %u", tc->first_tx_time);
+
 
   /*
    * 8) check delivery rate at time 11
@@ -1112,8 +1105,10 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
   TCP_TEST (tc->delivered_time == 11, "delivered time should be 11");
   TCP_TEST (tc->delivered == 7 * burst, "delivered should be %u is %u",
 	    7 * burst, tc->delivered);
-  /* Last rxt was at time 8 */
-  TCP_TEST (rs->interval_time == 3, "ack time should be 3 is %.2f",
+  /* Delivered time at retransmit was 8 so ack_time is 11 - 8 = 3. However,
+   * first_tx_time for rxt was 4 and rxt time was 9. Therefore snd_time
+   * is 9 - 4 = 5 */
+  TCP_TEST (rs->interval_time == 5, "ack time should be 5 is %.2f",
 	    rs->interval_time);
   /* delivered_now - delivered_rxt ~ 7 * burst - 3 * burst - 30.
    * That's because we didn't retransmit any new segment. */
@@ -1121,11 +1116,10 @@ tcp_test_delivery (vlib_main_t * vm, unformat_input_t * input)
 	    rs->delivered);
   TCP_TEST (rs->prior_delivered == 3 * burst + 30,
 	    "sample delivered should be %u", 3 * burst + 30);
-  TCP_TEST (approx_equal (rate, rs->tx_rate), "rate should be %u is %u", rate,
-	    rs->tx_rate);
   TCP_TEST (rs->flags & TCP_BTS_IS_RXT, "is retransmitted");
   TCP_TEST (rs->flags & TCP_BTS_IS_APP_LIMITED, "is app limited");
   TCP_TEST (tc->app_limited == 0, "app limited should be cleared");
+  TCP_TEST (tc->first_tx_time == 9, "first_tx_time %u", tc->first_tx_time);
 
   /*
    * 9) test flush
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 4c4a9a525af..227b3f8a856 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -240,7 +240,7 @@ typedef struct tcp_bt_sample_
   u64 delivered;		/**< Total delivered bytes for sample */
   f64 delivered_time;		/**< Delivered time when sample taken */
   f64 tx_time;			/**< Transmit time for the burst */
-  u64 tx_rate;			/**< Tx pacing rate */
+  f64 first_tx_time;		/**< Connection first tx time at tx */
   tcp_bts_flags_t flags;	/**< Sample flag */
 } tcp_bt_sample_t;
 
@@ -251,7 +251,6 @@ typedef struct tcp_rate_sample_
   f64 prior_time;		/**< Delivered time of sample used for rate */
   f64 interval_time;		/**< Time to ack the bytes delivered */
   f64 rtt_time;			/**< RTT for sample */
-  u64 tx_rate;			/**< Tx pacing rate */
   u32 delivered;		/**< Bytes delivered in interval_time */
   u32 acked_and_sacked;		/**< Bytes acked + sacked now */
   u32 lost;			/**< Bytes lost now */
@@ -394,6 +393,7 @@ typedef struct _tcp_connection
   u64 delivered;		/**< Total bytes delivered to peer */
   u64 app_limited;		/**< Delivered when app-limited detected */
   f64 delivered_time;		/**< Time last bytes were acked */
+  f64 first_tx_time;		/**< Send time for recently delivered/sent */
   tcp_byte_tracker_t *bt;	/**< Tx byte tracker */
 
   tcp_errors_t errors;	/**< Soft connection errors */
diff --git a/src/vnet/tcp/tcp_bt.c b/src/vnet/tcp/tcp_bt.c
index fe007543cd0..b550fdd65dd 100644
--- a/src/vnet/tcp/tcp_bt.c
+++ b/src/vnet/tcp/tcp_bt.c
@@ -241,8 +241,8 @@ tcp_bt_alloc_tx_sample (tcp_connection_t * tc, u32 min_seq)
   bts = bt_alloc_sample (tc->bt, min_seq);
   bts->delivered = tc->delivered;
   bts->delivered_time = tc->delivered_time;
-  bts->tx_rate = transport_connection_tx_pacer_rate (&tc->connection);
   bts->tx_time = tcp_time_now_us (tc->c_thread_index);
+  bts->first_tx_time = tc->first_tx_time;
   bts->flags |= tc->app_limited ? TCP_BTS_IS_APP_LIMITED : 0;
   return bts;
 }
@@ -270,7 +270,10 @@ tcp_bt_track_tx (tcp_connection_t * tc)
   u32 bts_index;
 
   if (tc->snd_una == tc->snd_nxt)
-    tc->delivered_time = tcp_time_now_us (tc->c_thread_index);
+    {
+      tc->delivered_time = tcp_time_now_us (tc->c_thread_index);
+      tc->first_tx_time = tc->delivered_time;
+    }
 
   bts = tcp_bt_alloc_tx_sample (tc, tc->snd_nxt);
   bts_index = bt_sample_index (bt, bts);
@@ -421,9 +424,10 @@ tcp_bt_sample_to_rate_sample (tcp_connection_t * tc, tcp_bt_sample_t * bts,
 
   rs->prior_delivered = bts->delivered;
   rs->prior_time = bts->delivered_time;
+  rs->interval_time = bts->tx_time - bts->first_tx_time;
   rs->rtt_time = bts->tx_time;
-  rs->tx_rate = bts->tx_rate;
   rs->flags = bts->flags;
+  tc->first_tx_time = bts->tx_time;
 }
 
 static void
@@ -529,7 +533,8 @@ tcp_bt_sample_delivery_rate (tcp_connection_t * tc, tcp_rate_sample_t * rs)
   if (tc->sack_sb.last_sacked_bytes)
     tcp_bt_walk_samples_ooo (tc, rs);
 
-  rs->interval_time = tc->delivered_time - rs->prior_time;
+  rs->interval_time = clib_max (tc->delivered_time - rs->prior_time,
+				rs->interval_time);
   rs->delivered = tc->delivered - rs->prior_delivered;
   rs->rtt_time = tc->delivered_time - rs->rtt_time;
   rs->acked_and_sacked = delivered;