dpdk: Add new DPDK stack to integrate with I/O services

docs: Update DPDK docs with new parameters:
Parameter names have had their hyphens changed to underscores, and
the I/O CPU argument is now named after the lcores and reflects
the naming used by DPDK.

transport: Add new udp_dpdk_link, based atop the new APIs:
This link is tightly coupled with the DPDK I/O service. The link class
carries all the address information to communicate with the other
host, and it can send packets directly through the DPDK NIC ports.

However, for receiving packets, the I/O service must pull the packets
from the DMA queue and attach them to the appropriate link object.
The link object merely formats the frame_buff object underneath, which
is embedded in the rte_mbuf container. For get_recv_buff, the link
will pull buffers only from its internal queue (the one filled by the
I/O service).

transport: Add DPDK-specific I/O service:
The I/O service is split into two parts, the user threads and the
I/O worker threads. The user threads submit requests through
various appropriate queues, and the I/O threads perform all the
I/O on their behalf. This includes routing UDP packets to the
correct receiver and getting the MAC address of a destination (by
performing the ARP request and handling the ARP replies).

The DPDK context stores I/O services. The context spawns all I/O
services on init(), and I/O services can be fetched from the dpdk_ctx
object by using a port ID.

I/O service clients:
The clients have two lockless ring buffers. One is to get a buffer
from the I/O service; the other is to release a buffer back to the
I/O service. Threads sleeping on buffer I/O are kept in a separate
list from the service queue and are processed in the course of doing
RX or TX.

The list nodes are embedded in the dpdk_io_if, and the head of the
list is on the dpdk_io_service. The I/O service will transfer the
embedded wait_req to the list if it cannot acquire the mutex to
complete the condition for waking.

Co-authored-by: Martin Braun <martin.braun@ettus.com>
Co-authored-by: Ciro Nishiguchi <ciro.nishiguchi@ni.com>
Co-authored-by: Brent Stapleton <brent.stapleton@ettus.com>

1 files changed, 29 insertions, 1 deletions

diff --git a/host/lib/include/uhdlib/transport/dpdk/service_queue.hpp b/host/lib/include/uhdlib/transport/dpdk/service_queue.hpp
index 7c9917079..c95786864 100644
--- a/host/lib/include/uhdlib/transport/dpdk/service_queue.hpp
+++ b/host/lib/include/uhdlib/transport/dpdk/service_queue.hpp
@@ -28,6 +28,14 @@ enum wait_type {
     WAIT_FLOW_OPEN,
     //! Wake once the flow/socket is destroyed
     WAIT_FLOW_CLOSE,
+    //! Wake once the new transport is connected
+    WAIT_XPORT_CONNECT,
+    //! Wake once the transport is disconnected
+    WAIT_XPORT_DISCONNECT,
+    //! Wake when MAC address found for IP address
+    WAIT_ARP,
+    //! Wake once the I/O worker terminates
+    WAIT_LCORE_TERM,
     //! Number of possible reasons for waiting
     WAIT_TYPE_COUNT
 };
@@ -50,6 +58,8 @@ struct wait_req
     std::mutex mutex;
     //! Whether the request was completed
     bool complete;
+    //! The status or error code associated with the request
+    int retval;
     //! An atomic reference counter for managing this request object's memory
     rte_atomic32_t refcnt;
 };
@@ -110,7 +120,7 @@ class service_queue
 public:
     /*!
      * Create a service queue
-     * \param depth Must be a power of 2
+     * \param depth Must be a power of 2. Actual size is less.
      * \param lcore_id The DPDK lcore_id associated with this service queue
      */
     service_queue(size_t depth, unsigned int lcore_id)
@@ -227,6 +237,24 @@ public:
         return stat;
     }
 
+    /*!
+     * Get the size of the service queue
+     * \return size of the service queue
+     */
+    inline size_t get_size()
+    {
+        return rte_ring_get_size(_waiter_ring);
+    }
+
+    /*!
+     * Get the capacity of the service queue
+     * \return capacity of the service queue
+     */
+    inline size_t get_capacity()
+    {
+        return rte_ring_get_capacity(_waiter_ring);
+    }
+
 private:
     //! Multi-producer, single-consumer ring for requests
     struct rte_ring* _waiter_ring;