On (Thu) Dec 17 2009 [23:44:49], Shirley Ma wrote:

virtio_net receives packets from its pre-allocated vring buffers, then it 
delivers these packets to upper layer protocols as skb buffs. So it's not
necessary to pre-allocate skb for each mergable buffer, then frees extra 
skbs when buffers are merged into a large packet. This patch has deferred 
skb allocation in receiving packets for both big packets and mergeable buffers
to reduce skb pre-allocations and skb frees. It frees unused buffers by calling 
detach_unused_buf in vring, so recv skb queue is not needed.

Signed-off-by: Shirley Ma <redacted>

...

+static void free_unused_bufs(struct virtnet_info *vi)
+{
+	void *buf;
+	while (vi->num) {
+		buf = vi->rvq->vq_ops->detach_unused_buf(vi->rvq);
+		if (!buf)
+			continue;

Do you mean 'break' here?

+		if (vi->mergeable_rx_bufs || vi->big_packets)
+			give_pages(vi, buf);
+		else
+			dev_kfree_skb(buf);
+		--vi->num;
+	}
+}
+

		Amit