3 ms·

Big fan of your books and blog! Would you say usefulness of dpdk and xdp has diminished purely from performance standpoint? I hear rumors you can do line rate

Big fan of your books and blog! Would you say usefulness of dpdk and xdp has diminished purely from performance standpoint? I hear rumors you can do line rate on modern linux kernels these days but haven’t had a chance to try it personally yet. I think at the time maglev was originally developed google was still on 2.6 kernels...

brendangregg 6y ago
Thanks. I'd expect more future uses of xdp over dpdk. As for max performance (I saw a Linux server max out multiple 10 GbE ports years ago) I'm not sure anyone right now knows what it is. We've recently added XDP, io_uring, BPF congestion control algorithms, and more. There are performance numbers for these in isolation, but I don't think anyone has performance tested (and tuned) them all working together yet. And that poses a problem: to reach maximum performance requires many engineering hours to learn and configure all of these. You'd need a large gain to justify doing this: E.g., for a system doing over 1M packets/s. This complexity may change. Look at BPF for observability: we built BCC and bpftrace so that using it was trivial. What trivial front-end/technology could we build upon XDP and io_uring to make deployment easy?
- bogomipz 6y ago
  >"I'd expect more future uses of xdp over dpdk." Can say why that is? I haven't really kept up with DPDK but I know there was lots of interest in it a few years back. What has changed?
  - deleted 6y ago
    [deleted]
  - wtallis 6y ago
    I haven't been watching the networking side too closely, but I expect the same thing to play out for storage with io_uring vs SPDK. When the in-kernel solution is almost as fast, has much broader availability and compatibility, and imposes fewer constraints on hardware purchasing decisions and system administration, the userspace offload solution gets consigned to a fairly small niche.
    - brendangregg 6y ago
      Right; there's a better presentation I can't find right now, but here's one from Intel showing how XDP was catching up in 2018 http://vger.kernel.org/lpc_net2018_talks/lpc18_pres_af_xdp_perf-v3.pdf http://vger.kernel.org/lpc_net2018_talks/lpc18_pres_af_xdp_p...
- LunaSea 6y ago
  Do you know how far along protocol implementation for higher layers like HTTP and TLS are?
- maartenh 6y ago
  How would you debug programs using ioring? With the traditional I/O syscalls, one can use tools like strace to observe the behavior of a program. Would using BPF to instrument the ioring be the way to go?

brendangregg 6y ago

Thanks. I'd expect more future uses of xdp over dpdk. As for max performance (I saw a Linux server max out multiple 10 GbE ports years ago) I'm not sure anyone right now knows what it is. We've recently added XDP, io_uring, BPF congestion control algorithms, and more. There are performance numbers for these in isolation, but I don't think anyone has performance tested (and tuned) them all working together yet. And that poses a problem: to reach maximum performance requires many engineering hours to learn and configure all of these. You'd need a large gain to justify doing this: E.g., for a system doing over 1M packets/s. This complexity may change. Look at BPF for observability: we built BCC and bpftrace so that using it was trivial. What trivial front-end/technology could we build upon XDP and io_uring to make deployment easy?

bogomipz 6y ago
>"I'd expect more future uses of xdp over dpdk." Can say why that is? I haven't really kept up with DPDK but I know there was lots of interest in it a few years back. What has changed?
- deleted 6y ago
  [deleted]
- wtallis 6y ago
  I haven't been watching the networking side too closely, but I expect the same thing to play out for storage with io_uring vs SPDK. When the in-kernel solution is almost as fast, has much broader availability and compatibility, and imposes fewer constraints on hardware purchasing decisions and system administration, the userspace offload solution gets consigned to a fairly small niche.
  - brendangregg 6y ago
    Right; there's a better presentation I can't find right now, but here's one from Intel showing how XDP was catching up in 2018 http://vger.kernel.org/lpc_net2018_talks/lpc18_pres_af_xdp_perf-v3.pdf http://vger.kernel.org/lpc_net2018_talks/lpc18_pres_af_xdp_p...
LunaSea 6y ago
Do you know how far along protocol implementation for higher layers like HTTP and TLS are?
maartenh 6y ago
How would you debug programs using ioring? With the traditional I/O syscalls, one can use tools like strace to observe the behavior of a program. Would using BPF to instrument the ioring be the way to go?