High Packet Loss in the Tx of TAP Interfaces

I was seeing some bond interfaces that had high dropped counts, but these were all Rx drops.

I noticed that the tap interfaces on OpenStack compute hosts - which were hooked to OpenContrail's vRouter - had drops on the Tx.

So, in trying to understand why we would be dropping packets on Tap interfaces, I did some poking around and found this link.

https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/ovs-dpdk_end_to_end_troubleshooting_guide/high_packet_loss_in_the_tx_queue_of_the_instance_s_tap_interface

From this, article, an excerpt:
"TX drops occur because of interference between the instance’s vCPU and other processes on the hypervisor. The TX queue of the tap interface is a buffer that can store packets for a short while in case that the instance cannot pick up the packets. This would happen if the instance’s CPU is prevented from running (or freezes) for a long enough time."

The article goes on and elaborates on diagnosis, and how to fix by adjusting the Tx Queue Length.