On Mon, Dec 28, 2020 at 02:51:09PM -0500, Willem de Bruijn wrote: > On Mon, Dec 28, 2020 at 12:29 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > On Mon, Dec 28, 2020 at 11:22:30AM -0500, Willem de Bruijn wrote: > > > From: Willem de Bruijn <willemb@xxxxxxxxxx> > > > > > > RFC for three new features to the virtio network device: > > > > > > 1. pass tx flow hash and state to host, for routing + telemetry > > > 2. pass rx tstamp to guest, for better RTT estimation > > > 3. pass tx tstamp to host, for accurate pacing > > > > > > All three would introduce an extension to the virtio spec. > > > I assume this would require opening three ballots against v1.2 at > > > https://www.oasis-open.org/committees/ballots.php?wg_abbrev=virtio > > > > > > This RFC is to informally discuss the proposals first. > > > > > > The patchset is against v5.10. Evaluation additionally requires > > > changes to qemu and at least one back-end. I implemented preliminary > > > support in Linux vhost-net. Both patches available through github at > > > > > > https://github.com/wdebruij/linux/tree/virtio-net-txhash-1 > > > https://github.com/wdebruij/qemu/tree/virtio-net-txhash-1 > > > > Any data on what the benefits are? > > For the general method, yes. For this specific implementation, not yet. > > Swift congestion control is delay based. It won the best paper award > at SIGCOMM this year. That paper has a lot of data: > https://dl.acm.org/doi/pdf/10.1145/3387514.3406591 . Section 3.1 talks > about the different components that contribute to delay and how to > isolate them. And for the hashing part? > BBR and BBRv2 also have an explicit ProbeRTT phase as part of the design. > > The specific additional benefits for VM-based TCP depends on many > conditions, e.g., whether a vCPU is exclusively owned and pinned. But > the same reasoning should be even more applicable to this even longer > stack, especially in the worst case conditions. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
