svm session vcl: per app rx message queues

Add option to use per app private segments for app to vpp message
queues, as opposed to exposing internal message queues segment.

When so configured, internal message queues are still polled by the
session queue node but external app message queues are handled by a new
input node (appsl-rx-mqs-input) that runs in interrupt state. Signaling
of the node, when mqs receive new messages, is done through eventfds
epolled by worker epoll input nodes.

Type: feature

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Iffe8ce5a9944a56a14e6d0f492a850cb9e392d16

src/svm/message_queue.c

@@ -482,7 +482,7 @@ int
 svm_msg_q_alloc_eventfd (svm_msg_q_t *mq)
 {
   int fd;
-  if ((fd = eventfd (0, EFD_NONBLOCK)) < 0)
+  if ((fd = eventfd (0, 0)) < 0)
     return -1;
   svm_msg_q_set_eventfd (mq, fd);
   return 0;