Hello I am trying to run pktgen on two VMs connected directly and using Virtio network cards. I created this configuration both on VirtualBox 5.2.8 and Libvirt/Qemu/KVM. On VirtualBox I use internal networks and on Libvirt I used tcp tunnel and bridged networks. In all of these configurations when I run pktgen and issue a command to start sending packets it sends packets only for a fraction of second for each port that I try. After that transmission stalls and only restarting pktgen allows to send some packets again for a fraction of second.
I created a bug on pktgen  but pktgen author advised me to contact Virtio driver authors here because he believes that this is not a problem of pktgen, but rather Virtio driver not freeing buffers. The problem is reproducible currently with DPDK 18.02 and pktgen 3.4.9 and was reproducible previously with DPDK 17.08 and pktgen 3.4.0. Can Virtio driver developers please comment on whether this is really a problem of Virtio driver and if it is going to be fixed?  https://github.com/pktgen/Pktgen-DPDK/issues/148