vcl: use events for epoll/select/read/write

Have vcl poll and wait on the event message queues as opposed to
constantly polling the session fifos. This also adds event signaling to
cut through sessions.

On the downside, because we can't wait on multiple condvars, i.e., when
we have multiple message queues because of cut-through registrations, we
do timed waits.

Change-Id: I29ade95dba449659fe46008bb1af502276a7c5fd
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 11 insertions, 11 deletions

diff --git a/src/svm/message_queue.c b/src/svm/message_queue.c
index 0f9be9c11b7..1b2d2e148ed 100644
--- a/src/svm/message_queue.c
+++ b/src/svm/message_queue.c
@@ -73,6 +73,7 @@ svm_msg_q_alloc (svm_msg_q_cfg_t * cfg)
       ring = &mq->rings[i];
       ring->elsize = cfg->ring_cfgs[i].elsize;
       ring->nitems = cfg->ring_cfgs[i].nitems;
+      ring->cursize = ring->head = ring->tail = 0;
       if (cfg->ring_cfgs[i].data)
 	ring->data = cfg->ring_cfgs[i].data;
       else
@@ -97,10 +98,10 @@ svm_msg_q_free (svm_msg_q_t * mq)
 svm_msg_q_msg_t
 svm_msg_q_alloc_msg_w_ring (svm_msg_q_t * mq, u32 ring_index)
 {
-  svm_msg_q_msg_t msg = {.as_u64 = ~0 };
+  svm_msg_q_msg_t msg;
   svm_msg_q_ring_t *ring = svm_msg_q_ring_inline (mq, ring_index);
 
-  ASSERT (ring->cursize != ring->nitems);
+  ASSERT (ring->cursize < ring->nitems);
   msg.ring_index = ring - mq->rings;
   msg.elt_index = ring->tail;
   ring->tail = (ring->tail + 1) % ring->nitems;
@@ -131,12 +132,9 @@ svm_msg_q_lock_and_alloc_msg_w_ring (svm_msg_q_t * mq, u32 ring_index,
   else
     {
       svm_msg_q_lock (mq);
+      while (svm_msg_q_ring_is_full (mq, ring_index))
+	svm_msg_q_wait (mq);
       *msg = svm_msg_q_alloc_msg_w_ring (mq, ring_index);
-      while (svm_msg_q_msg_is_invalid (msg))
-	{
-	  svm_msg_q_wait (mq);
-	  *msg = svm_msg_q_alloc_msg_w_ring (mq, ring_index);
-	}
     }
   return 0;
 }
@@ -190,18 +188,20 @@ svm_msg_q_free_msg (svm_msg_q_t * mq, svm_msg_q_msg_t * msg)
 static int
 svm_msq_q_msg_is_valid (svm_msg_q_t * mq, svm_msg_q_msg_t * msg)
 {
+  u32 dist1, dist2, tail, head;
   svm_msg_q_ring_t *ring;
-  u32 dist1, dist2;
 
   if (vec_len (mq->rings) <= msg->ring_index)
     return 0;
   ring = &mq->rings[msg->ring_index];
+  tail = ring->tail;
+  head = ring->head;
 
-  dist1 = ((ring->nitems + msg->elt_index) - ring->head) % ring->nitems;
-  if (ring->tail == ring->head)
+  dist1 = ((ring->nitems + msg->elt_index) - head) % ring->nitems;
+  if (tail == head)
     dist2 = (ring->cursize == 0) ? 0 : ring->nitems;
   else
-    dist2 = ((ring->nitems + ring->tail) - ring->head) % ring->nitems;
+    dist2 = ((ring->nitems + tail) - head) % ring->nitems;
   return (dist1 < dist2);
 }