X300: Change Ethernet buffering

Ethernet buffering is now done so that most of the buffering is done in
the socket buffers and multiple frames are only used to support the
receive side offload of the socket I/O.  Eliminates dropped packets at
high full duplex rates.

1 files changed, 32 insertions, 22 deletions

diff --git a/host/lib/transport/udp_zero_copy.cpp b/host/lib/transport/udp_zero_copy.cpp
index 29dbd6c1e..3b3760334 100644
--- a/host/lib/transport/udp_zero_copy.cpp
+++ b/host/lib/transport/udp_zero_copy.cpp
@@ -22,9 +22,6 @@ using namespace uhd;
 using namespace uhd::transport;
 namespace asio = boost::asio;
 
-//A reasonable number of frames for send/recv and async/sync
-//static const size_t DEFAULT_NUM_FRAMES = 32;
-
 /***********************************************************************
  * Check registry for correct fast-path setting (windows only)
  **********************************************************************/
@@ -211,7 +208,12 @@ public:
     }
 
     //set size for internal socket buffer
-    template <typename Opt> size_t resize_buff(size_t num_bytes){
+    template <typename Opt> size_t resize_buff(size_t num_bytes)
+    {
+        #if defined(UHD_PLATFORM_MACOS) || defined(UHD_PLATFORM_BSD)
+            //limit buffer resize on macos or it will error
+            num_bytes = std::min(num_bytes, MAX_BUFF_SIZE_ETH_MACOS);
+        #endif
         Opt option(num_bytes);
         _socket->set_option(option);
         return get_buff_size<Opt>();
@@ -316,26 +318,31 @@ udp_zero_copy::sptr udp_zero_copy::make(
     xport_params.num_recv_frames = size_t(hints.cast<double>("num_recv_frames", default_buff_args.num_recv_frames));
     xport_params.send_frame_size = size_t(hints.cast<double>("send_frame_size", default_buff_args.send_frame_size));
     xport_params.num_send_frames = size_t(hints.cast<double>("num_send_frames", default_buff_args.num_send_frames));
+    xport_params.recv_buff_size = size_t(hints.cast<double>("recv_buff_size", default_buff_args.recv_buff_size));
+    xport_params.send_buff_size = size_t(hints.cast<double>("send_buff_size", default_buff_args.send_buff_size));
 
-    //extract buffer size hints from the device addr
-    size_t usr_recv_buff_size = size_t(hints.cast<double>("recv_buff_size", xport_params.num_recv_frames * MAX_ETHERNET_MTU));
-    size_t usr_send_buff_size = size_t(hints.cast<double>("send_buff_size", xport_params.num_send_frames * MAX_ETHERNET_MTU));
-
-    if (hints.has_key("recv_buff_size")) {
-        if (usr_recv_buff_size < xport_params.num_recv_frames * MAX_ETHERNET_MTU) {
-            throw uhd::value_error((boost::format(
-                "recv_buff_size must be equal to or greater than %d")
-                % (xport_params.num_recv_frames * MAX_ETHERNET_MTU)).str());
-        }
+    // Preserve legacy defaults
+    if (xport_params.recv_buff_size == 0) {
+        xport_params.recv_buff_size = xport_params.num_recv_frames * xport_params.recv_frame_size;
+    }
+    if (xport_params.send_buff_size == 0) {
+        xport_params.send_buff_size = xport_params.num_recv_frames * xport_params.send_frame_size;
     }
+    
+    // Resize receive buffer due to known issue where Intel X710 uses full MTU for every packet regardless of actual size
+    xport_params.recv_buff_size = xport_params.recv_buff_size * MAX_ETHERNET_MTU / xport_params.recv_frame_size;
 
-    if (hints.has_key("send_buff_size")) {
-        if (usr_send_buff_size < xport_params.num_send_frames * MAX_ETHERNET_MTU) {
-            throw uhd::value_error((boost::format(
-                "send_buff_size must be equal to or greater than %d")
-                % (xport_params.num_send_frames * MAX_ETHERNET_MTU)).str());
+    #if defined(UHD_PLATFORM_MACOS) || defined(UHD_PLATFORM_BSD)
+        //limit default buffer size on macos to avoid the warning issued by resize_buff_helper
+        if (not hints.has_key("recv_buff_size") and xport_params.recv_buff_size > MAX_BUFF_SIZE_ETH_MACOS)
+        {
+            xport_params.recv_buff_size = MAX_BUFF_SIZE_ETH_MACOS;
         }
-    }
+        if (not hints.has_key("send_buff_size") and xport_params.send_buff_size > MAX_BUFF_SIZE_ETH_MACOS)
+        {
+            xport_params.send_buff_size = MAX_BUFF_SIZE_ETH_MACOS;
+        }
+    #endif
 
     udp_zero_copy_asio_impl::sptr udp_trans(
         new udp_zero_copy_asio_impl(addr, port, xport_params)
@@ -343,9 +350,12 @@ udp_zero_copy::sptr udp_zero_copy::make(
 
     //call the helper to resize send and recv buffers
     buff_params_out.recv_buff_size =
-        resize_buff_helper<asio::socket_base::receive_buffer_size>(udp_trans, usr_recv_buff_size, "recv");
+        resize_buff_helper<asio::socket_base::receive_buffer_size>(udp_trans, xport_params.recv_buff_size, "recv");
     buff_params_out.send_buff_size =
-        resize_buff_helper<asio::socket_base::send_buffer_size>   (udp_trans, usr_send_buff_size, "send");
+        resize_buff_helper<asio::socket_base::send_buffer_size>   (udp_trans, xport_params.send_buff_size, "send");
+
+    // Resize usable amount of receive buffer due to known issue where Intel X710 uses full MTU for every packet regardless of actual size
+    buff_params_out.recv_buff_size = buff_params_out.recv_buff_size * xport_params.recv_frame_size / MAX_ETHERNET_MTU;
 
     return udp_trans;
 }