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, 0 deletions

diff --git a/host/lib/include/uhdlib/transport/dpdk/arp.hpp b/host/lib/include/uhdlib/transport/dpdk/arp.hpp
new file mode 100644
index 000000000..e71119bb3
--- /dev/null
+++ b/host/lib/include/uhdlib/transport/dpdk/arp.hpp
@@ -0,0 +1,29 @@
+//
+// Copyright 2019 Ettus Research, a National Instruments brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+#ifndef _INCLUDED_UHDLIB_TRANSPORT_DPDK_ARP_HPP_
+#define _INCLUDED_UHDLIB_TRANSPORT_DPDK_ARP_HPP_
+
+#include <uhdlib/transport/dpdk/common.hpp>
+#include <uhdlib/transport/dpdk/service_queue.hpp>
+#include <rte_arp.h>
+
+namespace uhd { namespace transport { namespace dpdk {
+
+struct arp_request
+{
+    struct ether_addr tha;
+    port_id_t port;
+    ipv4_addr tpa;
+};
+
+struct arp_entry
+{
+    struct ether_addr mac_addr;
+    std::vector<wait_req*> reqs;
+};
+
+}}} /* namespace uhd::transport::dpdk */
+#endif /* _INCLUDED_UHDLIB_TRANSPORT_DPDK_ARP_HPP_ */