diff options
| -rw-r--r-- | host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp | 18 | ||||
| -rw-r--r-- | mpm/python/usrp_mpm/discovery.py | 8 |
2 files changed, 18 insertions, 8 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). diff --git a/mpm/python/usrp_mpm/discovery.py b/mpm/python/usrp_mpm/discovery.py index bae736150..c33f1e3c4 100644 --- a/mpm/python/usrp_mpm/discovery.py +++ b/mpm/python/usrp_mpm/discovery.py @@ -16,9 +16,9 @@ from usrp_mpm.mpmutils import to_binary_str RESPONSE_PREAMBLE = b"USRP-MPM" RESPONSE_SEP = b";" RESPONSE_CLAIMED_KEY = b"claimed" -# "Max MTU" is not a redundant name. We don't know the total path MTU, but we -# can say for sure that it won't exceed a certain value, and that's the max MTU -MAX_MTU = 8000 +# A buffer size large enough to capture any UDP packet we receive on the +# discovery socket +MAX_SOCK_BUFSIZ = 9000 # For setsockopt IP_MTU_DISCOVER = 10 IP_PMTUDISC_DO = 2 @@ -71,7 +71,7 @@ def _discovery_process(state, discovery_addr): try: while True: - data, sender = sock.recvfrom(MAX_MTU) + data, sender = sock.recvfrom(MAX_SOCK_BUFSIZ) log.debug("Got poked by: %s", sender[0]) # TODO this is still part of the awful subnet identification if not sender[0].startswith(discovery_addr_prefix): |