So, someone here can correct me about this if I'm wrong, but my impression is that DPDK's architecture sort of assumes single-purpose packet-processing servers --- it's commonly deployed with polling-mode drivers, right? So apart from the fact that DPDK would have required us to run another proxy daemon in userland, which was the thing we were trying to avoid doing, it also might have been tricky to get it to behave nicely on the same machines as our Rust edge proxies.

The nice thing about XDP is, you use llvm to make a .o, you load it with iproute2, and you forget about it; your code isn't a process running on the system, but rather a part of the Linux networking stack. It's as if the kernel just shipped with a "route Fly's UDP" feature.