On 2018/07/22 3:04, xiangxia.m.yue@gmail.com wrote:

From: Tonghao Zhang <redacted>

Factor out generic busy polling logic and will be
used for in tx path in the next patch. And with the patch,
qemu can set differently the busyloop_timeout for rx queue.

Signed-off-by: Tonghao Zhang <redacted>
---

...

+static void vhost_net_busy_poll_vq_check(struct vhost_net *net,
+					 struct vhost_virtqueue *rvq,
+					 struct vhost_virtqueue *tvq,
+					 bool rx)
+{
+	struct socket *sock = rvq->private_data;
+
+	if (rx) {
+		if (!vhost_vq_avail_empty(&net->dev, tvq)) {
+			vhost_poll_queue(&tvq->poll);
+		} else if (unlikely(vhost_enable_notify(&net->dev, tvq))) {
+			vhost_disable_notify(&net->dev, tvq);
+			vhost_poll_queue(&tvq->poll);
+		}
+	} else if ((sock && sk_has_rx_data(sock->sk)) &&
+		    !vhost_vq_avail_empty(&net->dev, rvq)) {
+		vhost_poll_queue(&rvq->poll);

Now we wait for vq_avail for rx as well, I think you cannot skip
vhost_enable_notify() on tx. Probably you might want to do:

} else if (sock && sk_has_rx_data(sock->sk)) {
	if (!vhost_vq_avail_empty(&net->dev, rvq)) {
		vhost_poll_queue(&rvq->poll);
	} else if (unlikely(vhost_enable_notify(&net->dev, rvq))) {
		vhost_disable_notify(&net->dev, rvq);
		vhost_poll_queue(&rvq->poll);
	}
}

Also it's better to care vhost_net_disable_vq()/vhost_net_enable_vq() on tx?

-- 
Toshiaki Makita