spaceywilly
3 hours ago
That’s very interesting, thank you for sharing. Looks like it could be a very useful tool for testing high performance networking.
I wonder if something similar could be done using TC BPF instead of AF_XDP? My only reservation about AF XDP is that it requires a special NIC to support it, so it may not be useful for a “regular Joe” user. I wonder if TC BPF would also work since it similarly bypasses the Kernel networking stack, I believe you can put packets directly into the NIC TX queue for transmission
tptacek
2 hours ago
You can, but the interesting thing about AF_XDP is that you've got a userland path to writing directly to the card's DMA buffers; TC BPF still allocates an skbuff for every packet you send.
Palomides
2 hours ago
it seems like every NIC on the market that can do 100Gb has support in its linux kernel driver, so probably not a big deal in practice
bgpdude
2 hours ago
you can use generic af_xdp which sits at the TC layer. Just get a bit less performance.
bgpdude
2 hours ago
That's what the veth examples are using