On Thu, 2011-03-17 at 07:02 +0200, Michael S. Tsirkin wrote:
> So, this just tries to make sure there's enough space for
> max packet in the ring, if not - drop and return OK.
> Why bother checking beforehand though?
> If that's what we want to do, we can just call add_buf and see
> if it fails?
In add_buf, there is an additional kick, see below. I added check
capacity to avoid this, thought it would be better performance. I will
retest it w/i add_buf to see the performance difference.
if (vq->num_free < out + in) {
pr_debug("Can't add buf len %i - avail = %i\n",
out + in, vq->num_free);
/* FIXME: for historical reasons, we force a notify here
if
* there are outgoing parts to the buffer. Presumably
the
* host should service the ring ASAP. */
if (out)
vq->notify(&vq->vq);
END_USE(vq);
return -ENOSPC;
}
Thanks
Shirley
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