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Wireblast a 100 Gbps packet generator in Go using AF_XDP
34 points by bgpdude 12 hours ago | 13 comments
  • spaceywilly
    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
      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
      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
      you can use generic af_xdp which sits at the TC layer. Just get a bit less performance.
      • bgpdude
        That's what the veth examples are using
  • bgpdude
    The video demo is pretty neat as well https://www.youtube.com/watch?v=8EmxvaOR5uA
  • barryvand
    ooh no more DPDK, this will make it a lot easier. I just started working with trex but it's all really complicated. Going to give this a try
    • tptacek
      I think, and I'm saying this in part to get someone to correct me, that post-XDP (so 5 years or so now) DPDK is basically obsolete. Is there a circumstance where it would make sense to start from DPDK rather than XDP?
      • bgpdude
        I think you're correct. Not really aware of any real limitations, other than it's slightly slower than dpdk (it's not a complete bypass), but at a much easier ease of use.
        • tptacek
          AF_XDP kind of is a complete bypass, right? RX get scooped right off the DMA buffer for the card, and TX get shoved right back in.
          • bgpdude
            Yeah fair point. I should have been more precise. AF_XDP with ZC bypasses the kernel networking stack and the NIC DMA's directly into UMEM and so in that sense it absolutely is a kernel bypass.

            The difference I was getting at vs DPDK is that the kernel NIC driver/NAPI/XDP path is still involvd. With DPDK the userspace PMD is effectively driving the NIC and accessing the queues directly.

            either way, it's great and everyone should use it :) that is assuming they have a use case for it. The use-cases are perhaps somewhat limited as it also bypasses the kernel tcp-ip stack, so you gotta do a lot yourself.