Hi,

         I am writing to inquire about the vring cleanup process during packets transmission.

In the virtio_xmit_pkts function, there is the following code:

         nb_used = virtqueue_nused(vq);

         if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))

                   virtio_xmit_cleanup(vq, nb_used);

In other words, cleaning is performed when the number of items used in the vring exceeds (vq->vq_nentries - vq->vq_free_thresh). In the case of an vring size of 4096, at least (4096-32) items need to be cleaned at once, which will take a considerable amount of time.

I'm curious why not clean up fewer items each time to avoid taking up too much CPU time in one transmission. Because during the debugging process, I found that cleaning up thousands of items at once takes up a considerable amount of time.

As I am not familiar with this process, I would appreciate it if you could provide me with some information on what its purpose is.

Best regards,

Zengyuan Wang