transport,usrp: Make available packet-based flow control

DPDK provides a fixed number of fixed-size buffers for the receive
window, so it needs packet-based flow control to avoid dropping
packets. This change enables counting by packets.

Co-authored-by: Ciro Nishiguchi <ciro.nishiguchi@ni.com>

1 files changed, 16 insertions, 11 deletions

diff --git a/host/lib/usrp/mpmd/mpmd_mb_iface.cpp b/host/lib/usrp/mpmd/mpmd_mb_iface.cpp
index cb779f635..b474dfdc3 100644
--- a/host/lib/usrp/mpmd/mpmd_mb_iface.cpp
+++ b/host/lib/usrp/mpmd/mpmd_mb_iface.cpp
@@ -167,7 +167,7 @@ uhd::rfnoc::chdr_ctrl_xport::sptr mpmd_mboard_impl::mpmd_mb_iface::make_ctrl_tra
     const size_t link_idx = _local_device_id_map.at(local_device_id);
     uhd::transport::send_link_if::sptr send_link;
     uhd::transport::recv_link_if::sptr recv_link;
-    std::tie(send_link, std::ignore, recv_link, std::ignore, std::ignore) =
+    std::tie(send_link, std::ignore, recv_link, std::ignore, std::ignore, std::ignore) =
         _link_if_mgr->get_link(
             link_idx, uhd::transport::link_type_t::CTRL, uhd::device_addr_t());
 
@@ -209,25 +209,30 @@ mpmd_mboard_impl::mpmd_mb_iface::make_rx_data_transport(
 
     uhd::transport::send_link_if::sptr send_link;
     uhd::transport::recv_link_if::sptr recv_link;
-    bool lossy_xport;
+    bool lossy_xport, packet_fc;
     size_t recv_buff_size;
-    std::tie(send_link, std::ignore, recv_link, recv_buff_size, lossy_xport) =
+    std::tie(send_link, std::ignore, recv_link, recv_buff_size, lossy_xport, packet_fc) =
         _link_if_mgr->get_link(
             link_idx, uhd::transport::link_type_t::RX_DATA, xport_args);
 
     /* Associate local device ID with the adapter */
     _adapter_map[local_sep_addr.first] = send_link->get_send_adapter_id();
 
-    // TODO: configure this based on the transport type
-    const stream_buff_params_t recv_capacity = {
-        recv_buff_size, uhd::rfnoc::MAX_FC_CAPACITY_PKTS};
+    const uhd::rfnoc::stream_buff_params_t recv_capacity = {recv_buff_size,
+        packet_fc ? static_cast<uint32_t>(recv_link->get_num_recv_frames())
+                  : uhd::rfnoc::MAX_FC_CAPACITY_PKTS};
 
     const double ratio = 1.0 / 32;
 
-    // Configure flow control frequency to use bytes only for UDP
-    stream_buff_params_t fc_freq = {
-        static_cast<uint64_t>(std::ceil(double(recv_buff_size) * ratio)),
-        uhd::rfnoc::MAX_FC_FREQ_PKTS};
+    // Configure flow control frequency to use either bytes only or packets only
+    uhd::rfnoc::stream_buff_params_t fc_freq;
+    if (packet_fc) {
+        fc_freq = {uhd::rfnoc::MAX_FC_FREQ_BYTES,
+            static_cast<uint32_t>(std::ceil(recv_link->get_num_recv_frames() * ratio))};
+    } else {
+        fc_freq = {static_cast<uint64_t>(std::ceil(double(recv_buff_size) * ratio)),
+            uhd::rfnoc::MAX_FC_FREQ_PKTS};
+    }
 
     stream_buff_params_t fc_headroom = {0, 0};
 
@@ -293,7 +298,7 @@ mpmd_mboard_impl::mpmd_mb_iface::make_tx_data_transport(
     uhd::transport::send_link_if::sptr send_link;
     uhd::transport::recv_link_if::sptr recv_link;
     bool lossy_xport;
-    std::tie(send_link, std::ignore, recv_link, std::ignore, lossy_xport) =
+    std::tie(send_link, std::ignore, recv_link, std::ignore, lossy_xport, std::ignore) =
         _link_if_mgr->get_link(
             link_idx, uhd::transport::link_type_t::TX_DATA, xport_args);