Using the new bridges of FreeBSD 15

(blog.feld.me)

67 points | by vermaden 7 hours ago ago

19 comments

  • j16sdiz 3 hours ago

    Why sudden surge of FreeBSD-related posts?

    Did anything special or new happened on FreeBSD land?

    • kev009 3 hours ago

      15.0 was released a couple months ago, hence the title.

      • j16sdiz 3 hours ago

        We have three (including this) FreeBSD posts in the past two days.

        Back to FreeBSD: Part 1 (hypha.pub) https://news.ycombinator.com/item?id=47108989

        Linuxulator on FreeBSD Feels Like Magic (hayzam.com) https://news.ycombinator.com/item?id=47113527

        • kev009 3 hours ago

          Generally people get more excited any time a major release of anything comes out. But FWIW HN has always had favorable front paging for anything related to FreeBSD and OpenBSD.

        • unethical_ban an hour ago

          No conspiracy, I think it just happens. One person posts something, maybe someone else reads it and gets into a rabbit hole on a topic, or maybe someone sees an opportunity to throw more conversation pieces at something hot.

  • ggm 6 hours ago

    When this settles down, I look forward to all of jail/iojail, Sylve, Bastille, Bhyve documenting this in a mutually consistent manner. As it stands, I have managed to completely knot my brain over the abstractions, what is happening. It's me, not the systems, but I think there is a little bit of "meh, I understand it, so it must be obvious to anyone smart" going on, and alas, I am not smart, and I get confused easily.

    I'm in bastille atm, but have been in all of them and TrueNAS core. and libvirt over on the other unix.

  • shashasha2 7 hours ago

    Bhyve bridges are inefficient: every packet traverses NIC β†’ CPU β†’ bridge β†’ VM, adding unnecessary copies that kill throughput. Switching to SR-IOV eliminated that overhead and I saturated the 10 GbE link.

    • Veserv 5 hours ago

      I do not see how that follows. Memory bandwidth is measured in the hundreds of Gb/s. You can issue tens of unnecessary full memory copies before you bottleneck at a paltry 10 Gb/s.

      It is much more likely there is something else terribly wrong in a network stack if it can not even drive a measly 10 Gb/s.

      • stingraycharles 5 hours ago

        That assumes memory bandwidth is the issue, and not latency and/or CPU.

    • kev009 3 hours ago

      It would benefit from a batching mechanism.

    • assimpleaspossi 6 hours ago

      You used the new optimized bridges on FreeBSD 15?

      • crest 17 minutes ago

        The bridge driver gained features (vlan filtering) not performance.

    • gigatexal 6 hours ago

      On Linux?

  • waynesonfire 5 hours ago

    > -tso4 -tso6 -vlanhwfilter -vlanmtu -vlanhwtso -vlanhwtag -vlanhwcsum -lro

    Whys the author disabling tso and lro? Whats the motivation?

    I'm not familiar with the other flags.

    • crest 16 minutes ago

      LRO because the bridge has to forward the real frames. TSO because it’s fairly useless now.

    • kev009 3 hours ago

      People found this worked in the past and it gets copied around. There is no reason to disable some of this. Bridge will automatically disable LRO and find the common set of other offloads. TSO is not useful for a bridged guest.

    • j16sdiz 3 hours ago

      Looks like TSO does not support VLAN. Not sure about lro.

  • bzmrgonz 5 hours ago

    I for one welcome and applaud any progress on the bsd front,and this seems to be huge.