[libfabric-users] udp packets and jumbo frames

[Martin Pokorny]

Hello,

The application I'm working on needs to support an Ethernet 
network configured with jumbo frames to capture data in UDP 
packets, where each UDP packet fits into a single Ethernet jumbo 
frame. I'd like to use libfabric for this configuration, as I've 
already got an implementation based on libfabric for other 
providers. However, it seems that the value of 
`udpx_ep_attr.max_msg_size` defined in `prov/udp/src/udpx_attr.c` 
is hard-coded to 1472, which prevents using UDP packets with a 
larger payload. I don't know that this value could be determined 
from the Ethernet configuration at runtime, but as I'd be happy to 
have it set at compile time, would a possible approach to 
supporting jumbo frames of a known size be to increase that value 
appropriately? I don't think that `udpx_tx_attr.size`, 
`udpx_tx_attr.inject_size`, and `udpx_rx_attr.size` would need to 
change, but I'm less certain about that. In any case, I'm not 
trying to implement the most general, "correct" solution at this 
time, and I'm happy to patch some source files specifically for my 
needs. If anyone could offer any advice about what I'm trying to 
do, I'd appreciate it. TIA.

--
Martin