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, 2 insertions, 2 deletions

diff --git a/host/lib/include/uhdlib/transport/link_base.hpp b/host/lib/include/uhdlib/transport/link_base.hpp
index e4d329e2a..a57b681ca 100644
--- a/host/lib/include/uhdlib/transport/link_base.hpp
+++ b/host/lib/include/uhdlib/transport/link_base.hpp
@@ -56,7 +56,7 @@ private:
  * the link interface methods.
  *
  * This template requires the following methods in the derived class:
- *   bool get_send_buf_derived(frame_buff& buf, int32_t timeout_ms);
+ *   bool get_send_buff_derived(frame_buff& buf, int32_t timeout_ms);
  *   void release_send_buf_derived(frame_buff& buf);
  *
  * Additionally, the subclass must call preload_free_buf for each frame_buff
@@ -145,7 +145,7 @@ private:
  * the link interface methods.
  *
  * This template requires the following methods in the derived class:
- *   bool get_recv_buff_derived(frame_buff& buff, int32_t timeout_ms);
+ *   size_t get_recv_buff_derived(frame_buff& buff, int32_t timeout_ms);
  *   void release_recv_buff_derived(frame_buff& buff);
  *
  * Additionally, the subclass must call preload_free_buff for each