diff options
Diffstat (limited to 'host')
| -rw-r--r-- | host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp b/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp index 89f713f1e..fe7d2b670 100644 --- a/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp +++ b/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp @@ -29,14 +29,24 @@ using namespace uhd::mpmd::xport; namespace { -//! Maximum CHDR packet size in bytes -const size_t MPMD_10GE_DATA_FRAME_MAX_SIZE = 7972; -const size_t MPMD_1GE_DATA_FRAME_MAX_SIZE = 1472; +//! Maximum CHDR packet size in bytes. +// Our 10GbE connections use custom FPGA code which caps frames at 8192 bytes. +// However, we artificially limit this to a smaller frame size, which gives us +// a safety margin. +const size_t MPMD_10GE_DATA_FRAME_MAX_SIZE = 8016; +// For 1 GbE, we either go through our on-chip PHY/MAC, which also caps at 8192 +// bytes, or we go through the RJ45, and then the DMA to the chip, which can go +// higher. We thus choose the same value as for 10 GbE. +// Note that for 1 GbE, we almost always have an MTU of 1500, so we will rarely +// meet this frame size, but MTU discovery will take care of that. This is just +// a cap to make sure we never try CHDR packets that will clog our fabric. +const size_t MPMD_1GE_DATA_FRAME_MAX_SIZE = 8016; //! Number of send/recv frames const size_t MPMD_ETH_NUM_FRAMES = 32; -//! +//! Buffer depth in seconds. We use the link rate to determine how large buffers +// must be to store this many seconds worth of data. const double MPMD_BUFFER_DEPTH = 20.0e-3; // s //! For MTU discovery, the time we wait for a packet before calling it // oversized (seconds). |