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>

3 files changed, 44 insertions, 18 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);
 }
 
diff --git a/src/svm/message_queue.h b/src/svm/message_queue.h
index e4a5f07d480..4c16c97ca7c 100644
--- a/src/svm/message_queue.h
+++ b/src/svm/message_queue.h
@@ -22,6 +22,7 @@
 
 #include <vppinfra/clib.h>
 #include <vppinfra/error.h>
+#include <vppinfra/time.h>
 #include <svm/queue.h>
 
 typedef struct svm_msg_q_ring_
@@ -274,12 +275,6 @@ svm_msg_q_lock (svm_msg_q_t * mq)
   return pthread_mutex_lock (&mq->q->mutex);
 }
 
-static inline void
-svm_msg_q_wait (svm_msg_q_t * mq)
-{
-  pthread_cond_wait (&mq->q->condvar, &mq->q->mutex);
-}
-
 /**
  * Unlock message queue
  */
@@ -292,6 +287,37 @@ svm_msg_q_unlock (svm_msg_q_t * mq)
   pthread_mutex_unlock (&mq->q->mutex);
 }
 
+/**
+ * Wait for message queue event
+ *
+ * Must be called with mutex held
+ */
+static inline void
+svm_msg_q_wait (svm_msg_q_t * mq)
+{
+  pthread_cond_wait (&mq->q->condvar, &mq->q->mutex);
+}
+
+/**
+ * Timed wait for message queue event
+ *
+ * Must be called with mutex held.
+ *
+ * @param mq 		message queue
+ * @param timeout	time in seconds
+ */
+static inline int
+svm_msg_q_timedwait (svm_msg_q_t * mq, double timeout)
+{
+  struct timespec ts;
+
+  ts.tv_sec = unix_time_now () + (u32) timeout;
+  ts.tv_nsec = (timeout - (u32) timeout) * 1e9;
+  if (pthread_cond_timedwait (&mq->q->condvar, &mq->q->mutex, &ts))
+    return -1;
+  return 0;
+}
+
 #endif /* SRC_SVM_MESSAGE_QUEUE_H_ */
 
 /*
diff --git a/src/svm/svm_fifo.c b/src/svm/svm_fifo.c
index 47df22547ac..018827e0343 100644
--- a/src/svm/svm_fifo.c
+++ b/src/svm/svm_fifo.c
@@ -179,7 +179,7 @@ format_svm_fifo (u8 * s, va_list * args)
 
   if (verbose > 1)
     s = format
-      (s, " server session %d thread %d client session %d thread %d\n",
+      (s, " vpp session %d thread %d app session %d thread %d\n",
        f->master_session_index, f->master_thread_index,
        f->client_session_index, f->client_thread_index);