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virtio_net: Recycle some more rx buffer pages

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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: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (use netdev_priv)
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mark McLoughlin 2008-11-16 22:39:18 -08:00 committed by David S. Miller
parent 908cd2dabb
commit 0a888fd1f6
1 changed files with 13 additions and 9 deletions
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22
drivers/net/virtio_net.c
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@ -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;
}