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ovs performance between two vms on same host

I have 2 vms over the same host (compute).
Both vms have these vNICs attached:

  • pci-passthrough 10Gbps (vNIC1)
  • virtio (ovs) (vNIC2)

The traffic flows as follows:

Traffic generator -> pNIC -> [vm1 vNIC1 (passthrough) -> fwd -> vNIC2] -> OVS -> [vm2 vNIC2]

Because vNIC1 is passthrough, I can get to 10Gbps when redirecting back to vNIC1. But redirecting through OVS puts traffic down to 150Mbps.
I'm aware this is not ovs-dpdk, but as I've seen here it should get up to 1.1Gbps for 64B packets.

This is my host (compute):

  • Intel(R) Xeon(R) CPU X5650 @ 2.67GHz
  • 24 CPUs (HT)
  • VT-x enabled
  • 32GB ram
  • Isolated cpus

Both the vms have

  • 8 GB ram
  • 3 CPU pinning (actually only 1 works redirecting the traffic)

All sibling-cpus are idle. I mean, I treat it as non-HT machine.

I'm using openstack rocky.

# ovs-vswitchd --version
ovs-vswitchd (Open vSwitch) 2.10.0

Is there anything I can do to boost native OVS performance? Doesn't 150Mbps looks a bit slow?