Hi Ciara, > Thanks for your feedback. The limitation is only placed on phy port queues on > the VP (vhost -> phy) path. VV path and PV path are not > affected.
Yes, you are right. VM to VM traffic is copied on transmit to the second VM. > > I would much rather put a requirement on tenants that their virtio drivers > > need to allocate enough virtio packet buffers if they want their VM to use > > zero-copy vhostuser ports. Or is the critical resource owned and managed by > > Qemu and we'd need a patch on Qemu to overcome this limit? Can you comment on that? Can a user also reduce the problem by configuring a) a larger virtio Tx queue size (up to 1K) in Qemu, or b) a larger mempool for packets in Tx direction inside the guest (driver?) > > > > And what about increased packet drop risk due to shortened tx queues? > > I guess this could be an issue. If I had some data to back this up I would > include it in the documentation and mention the risk. > If the risk is unacceptable to the user they may choose to not enable the > feature. It's disabled by default so shouldn't introduce an issue for > the standard case. Yes, but it would be good to understand the potential drawback for a better judgement of the trade-off between better raw throughput and higher loss risk. Regards, Jan _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
