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Commit 0a888fd1 authored by Mark McLoughlin's avatar Mark McLoughlin Committed by David S. Miller
Browse files

virtio_net: Recycle some more rx buffer pages 



Each time we re-fill the recv queue with buffers, we allocate
one too many skbs and free it again when adding fails. We should
recycle the pages allocated in this case.

A previous version of this patch made trim_pages() trim trailing
unused pages from skbs with some paged data, but this actually
caused a barely measurable slowdown.

Signed-off-by: default avatarMark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (use netdev_priv)
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 908cd2da

drivers/net/virtio_net.c

+13 −9
Original line number Diff line number Diff line
@@ -82,6 +82,16 @@ static void give_a_page(struct virtnet_info *vi, struct page *page) 
	vi->pages = page;

}



static void trim_pages(struct virtnet_info *vi, struct sk_buff *skb)

{

	unsigned int i;



	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)

		give_a_page(vi, skb_shinfo(skb)->frags[i].page);

	skb_shinfo(skb)->nr_frags = 0;

	skb->data_len = 0;

}



static struct page *get_a_page(struct virtnet_info *vi, gfp_t gfp_mask)

{

	struct page *p = vi->pages;
@@ -121,15 +131,8 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb, 
	}

	len -= sizeof(struct virtio_net_hdr);



	if (len <= MAX_PACKET_LEN) {

		unsigned int i;



		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)

			give_a_page(netdev_priv(dev),

				    skb_shinfo(skb)->frags[i].page);

		skb->data_len = 0;

		skb_shinfo(skb)->nr_frags = 0;

	}

	if (len <= MAX_PACKET_LEN)

		trim_pages(netdev_priv(dev), skb);



	err = pskb_trim(skb, len);

	if (err) {
@@ -233,6 +236,7 @@ static void try_fill_recv(struct virtnet_info *vi) 
		err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);

		if (err) {

			skb_unlink(skb, &vi->recv);

			trim_pages(vi, skb);

			kfree_skb(skb);

			break;

		}