TCP cc/window management fixes and debugging

- added persist timer
- update rcv_las whenever sending an ack
- moved fifo size to its own cache line
- improved session and builtin client debugging

Change-Id: Ia649cf942cf0c061a713e8b67f0eb6974a6cd55b
Signed-off-by: Florin Coras <fcoras@cisco.com>
Signed-off-by: Dave Barach <dave@barachs.net>

4 files changed, 61 insertions, 13 deletions

diff --git a/src/vnet/session/node.c b/src/vnet/session/node.c
index 8681105c284..b86e87d9bac 100644
--- a/src/vnet/session/node.c
+++ b/src/vnet/session/node.c
@@ -119,15 +119,20 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 
   /* Nothing to read return */
   if (max_dequeue0 == 0)
-    {
-      return 0;
-    }
+    return 0;
 
   /* Ensure we're not writing more than transport window allows */
-  max_len_to_snd0 = clib_min (max_dequeue0, snd_space0);
-
-  /* TODO check if transport is willing to send len_to_snd0
-   * bytes (Nagle) */
+  if (max_dequeue0 < snd_space0)
+    {
+      /* Constrained by tx queue. Try to send only fully formed segments */
+      max_len_to_snd0 = (max_dequeue0 > snd_mss0) ?
+	max_dequeue0 - max_dequeue0 % snd_mss0 : max_dequeue0;
+      /* TODO Nagle ? */
+    }
+  else
+    {
+      max_len_to_snd0 = snd_space0;
+    }
 
   n_frame_bytes = snd_mss0 * VLIB_FRAME_SIZE;
   n_frames_per_evt = ceil ((double) max_len_to_snd0 / n_frame_bytes);
@@ -308,11 +313,14 @@ session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
   int n_tx_packets = 0;
   u32 my_thread_index = vm->cpu_index;
   int i, rv;
+  f64 now = vlib_time_now (vm);
+
+  SESSION_EVT_DBG (SESSION_EVT_POLL_GAP_TRACK, smm, my_thread_index);
 
   /*
    *  Update TCP time
    */
-  tcp_update_time (vlib_time_now (vm), my_thread_index);
+  tcp_update_time (now, my_thread_index);
 
   /*
    * Get vpp queue events
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index f10918aa3c4..8e2b2616f58 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -556,7 +556,7 @@ session_manager_allocate_session_fifos (session_manager_main_t * smm,
 					u8 * added_a_segment)
 {
   svm_fifo_segment_private_t *fifo_segment;
-  u32 fifo_size, default_fifo_size = 128 << 10;	/* TODO config */
+  u32 fifo_size, default_fifo_size = 1 << 16;	/* TODO config */
   int i;
 
   *added_a_segment = 0;
@@ -1293,6 +1293,10 @@ session_manager_main_enable (vlib_main_t * vm)
   vec_validate (smm->current_enqueue_epoch, num_threads - 1);
   vec_validate (smm->vpp_event_queues, num_threads - 1);
 
+#if SESSION_DBG
+  vec_validate (smm->last_event_poll_by_thread, num_threads - 1);
+#endif
+
   /* $$$$ preallocate hack config parameter */
   for (i = 0; i < 200000; i++)
     {
diff --git a/src/vnet/session/session.h b/src/vnet/session/session.h
index a39bc06ffca..6878b4d25c8 100644
--- a/src/vnet/session/session.h
+++ b/src/vnet/session/session.h
@@ -20,6 +20,7 @@
 #include <vlibmemory/api.h>
 #include <vppinfra/sparse_vec.h>
 #include <svm/svm_fifo_segment.h>
+#include <vnet/session/session_debug.h>
 
 #define HALF_OPEN_LOOKUP_INVALID_VALUE ((u64)~0)
 #define INVALID_INDEX ((u32)~0)
@@ -36,7 +37,7 @@ typedef enum
   FIFO_EVENT_BUILTIN_RX
 } fifo_event_type_t;
 
-#define foreach_session_input_error                                         \
+#define foreach_session_input_error                                    	\
 _(NO_SESSION, "No session drops")                                       \
 _(NO_LISTENER, "No listener for dst port drops")                        \
 _(ENQUEUED, "Packets pushed into rx fifo")                              \
@@ -218,6 +219,15 @@ struct _session_manager_main
   /* Convenience */
   vlib_main_t *vlib_main;
   vnet_main_t *vnet_main;
+
+#if SESSION_DBG
+  /**
+   * last event poll time by thread
+   * Debug only. Will cause false cache-line sharing as-is
+   */
+  f64 *last_event_poll_by_thread;
+#endif
+
 };
 
 extern session_manager_main_t session_manager_main;
diff --git a/src/vnet/session/session_debug.h b/src/vnet/session/session_debug.h
index 80a97cd5f09..eb11f1a00b9 100644
--- a/src/vnet/session/session_debug.h
+++ b/src/vnet/session/session_debug.h
@@ -16,13 +16,13 @@
 #define SRC_VNET_SESSION_SESSION_DEBUG_H_
 
 #include <vnet/session/transport.h>
-#include <vnet/session/session.h>
 #include <vlib/vlib.h>
 
 #define foreach_session_dbg_evt		\
   _(ENQ, "enqueue")			\
   _(DEQ, "dequeue")			\
-  _(DEQ_NODE, "dequeue")
+  _(DEQ_NODE, "dequeue")		\
+  _(POLL_GAP_TRACK, "poll gap track")	\
 
 typedef enum _session_evt_dbg
 {
@@ -33,6 +33,7 @@ typedef enum _session_evt_dbg
 
 #define SESSION_DBG (0)
 #define SESSION_DEQ_NODE_EVTS (0)
+#define SESSION_EVT_POLL_DBG (1)
 
 #if TRANSPORT_DEBUG && SESSION_DBG
 
@@ -97,9 +98,34 @@ typedef enum _session_evt_dbg
 #define SESSION_EVT_DEQ_NODE_HANDLER(_node_evt)
 #endif
 
+#if SESSION_DBG && SESSION_EVT_POLL_DBG
+#define SESSION_EVT_POLL_GAP(_smm, _my_thread_index)			\
+{									\
+  ELOG_TYPE_DECLARE (_e) =						\
+  {									\
+    .format = "nixon-gap: %d MS",					\
+    .format_args = "i4",						\
+  };									\
+  DEC_SESSION_ED(_e, 1);						\
+  ed->data[0] =	(u32) ((now -						\
+    _smm->last_event_poll_by_thread[my_thread_index])*1000.0);		\
+}
+#define SESSION_EVT_POLL_GAP_TRACK_HANDLER(_smm, _my_thread_index)	\
+{									\
+  if (PREDICT_TRUE(							\
+	      smm->last_event_poll_by_thread[my_thread_index] != 0.0))	\
+    if (now > smm->last_event_poll_by_thread[_my_thread_index] + 500e-6)\
+	SESSION_EVT_POLL_GAP(smm, my_thread_index);			\
+  _smm->last_event_poll_by_thread[my_thread_index] = now;		\
+}
+
+#else
+#define SESSION_EVT_POLL_GAP(_smm, _my_thread_index)
+#define SESSION_EVT_POLL_GAP_TRACK_HANDLER(_smm, _my_thread_index)
+#endif
+
 #define CONCAT_HELPER(_a, _b) _a##_b
 #define CC(_a, _b) CONCAT_HELPER(_a, _b)
-
 #define SESSION_EVT_DBG(_evt, _args...) CC(_evt, _HANDLER)(_args)
 
 #else