From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark McLoughlin Subject: [PATCH 1/2] virtio_net: Recycle some more rx buffer pages Date: Wed, 8 Oct 2008 20:34:58 +0100 Message-ID: <1223494499-18732-1-git-send-email-markmc@redhat.com> Return-path: In-Reply-To: <> References: <> Sender: linux-kernel-owner@vger.kernel.org To: Rusty Russell Cc: linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, Mark McLoughlin List-Id: virtualization@lists.linuxfoundation.org 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 --- drivers/net/virtio_net.c | 21 +++++++++++++-------- 1 files changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0196a0d..985271a 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -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; @@ -121,14 +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(dev->priv, skb_shinfo(skb)->frags[i].page); - skb->data_len = 0; - skb_shinfo(skb)->nr_frags = 0; - } + if (len <= MAX_PACKET_LEN) + trim_pages(dev->priv, skb); err = pskb_trim(skb, len); if (err) { @@ -232,6 +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; } -- 1.5.4.3