Created attachment 319 [details]
viritio patch

In a virtual machine scenario running a DPDK application with virtio drivers,
when the host machine adjusted the guest VM's transmit/receive queue size from
1024 to 4096, the DPDK application's allocated 2048 mbufs became insufficient.
After this adjustment, the condition vq->vq_nentries - vq->vq_free_thresh was
never triggered, resulting in the cleanup operation not occurring.

virtio_dev_rx_queue_setup the third param nb_desc is not used when
vq->vq_free_cnt great then nb_desc. vq->vq_free_cnt is assigned a value through
vq->n_nentries when virtio driver has inited. i40e driver vq has a nb_rx_desc
value, our dpdk app nb_desc setup 2048, malloc 2048 mbufs, so our dpdk app
rx/tx burst is failed on the line.