From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCH 1/3] virtio_net: Recycle some more rx buffer pages Date: Mon, 17 Nov 2008 17:35:43 +1030 Message-ID: <200811171735.44025.rusty@rustcorp.com.au> References: <200811171344.57410.rusty@rustcorp.com.au> <20081116.194505.140648013.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, markmc@redhat.com To: David Miller Return-path: Received: from ozlabs.org ([203.10.76.45]:53693 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752010AbYKQHFu (ORCPT ); Mon, 17 Nov 2008 02:05:50 -0500 In-Reply-To: <20081116.194505.140648013.davem@davemloft.net> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: On Monday 17 November 2008 14:15:05 David Miller wrote: > From: Rusty Russell > Date: Mon, 17 Nov 2008 13:44:57 +1030 > > > @@ -82,6 +82,16 @@ static void give_a_page(struct virtnet_info *vi, > > struct page *page) > > -E_EMAIL_CLIENT_NEWLINES From: Mark McLoughlin 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 Signed-off-by: Rusty Russell (use netdev_priv) --- drivers/net/virtio_net.c | 21 +++++++++++++-------- 1 file 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(netdev_priv(dev), 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; }