From d7e8883cfcf4851afe74fb380cc62b7fa9cf66ba Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 30 Apr 2012 08:10:34 +0000 Subject: net: make GRO aware of skb->head_frag MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit GRO can check if skb to be merged has its skb->head mapped to a page fragment, instead of a kmalloc() area. We 'upgrade' skb->head as a fragment in itself This avoids the frag_list fallback, and permits to build true GRO skb (one sk_buff and up to 16 fragments), using less memory. This reduces number of cache misses when user makes its copy, since a single sk_buff is fetched. This is a followup of patch "net: allow skb->head to be a page fragment" Signed-off-by: Eric Dumazet Cc: Ilpo Järvinen Cc: Herbert Xu Cc: Maciej Żenczykowski Cc: Neal Cardwell Cc: Tom Herbert Cc: Jeff Kirsher Cc: Ben Hutchings Cc: Matt Carlson Cc: Michael Chan Signed-off-by: David S. Miller --- net/core/skbuff.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) (limited to 'net/core/skbuff.c') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index effa75d0e318..09cc38651b2f 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -69,7 +69,7 @@ #include #include -static struct kmem_cache *skbuff_head_cache __read_mostly; +struct kmem_cache *skbuff_head_cache __read_mostly; static struct kmem_cache *skbuff_fclone_cache __read_mostly; static void sock_pipe_buf_release(struct pipe_inode_info *pipe, @@ -2901,6 +2901,31 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) NAPI_GRO_CB(skb)->free = 1; goto done; + } else if (skb->head_frag) { + int nr_frags = pinfo->nr_frags; + skb_frag_t *frag = pinfo->frags + nr_frags; + struct page *page = virt_to_head_page(skb->head); + unsigned int first_size = headlen - offset; + unsigned int first_offset; + + if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS) + return -E2BIG; + + first_offset = skb->data - + (unsigned char *)page_address(page) + + offset; + + pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags; + + frag->page.p = page; + frag->page_offset = first_offset; + skb_frag_size_set(frag, first_size); + + memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags); + /* We dont need to clear skbinfo->nr_frags here */ + + NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD; + goto done; } else if (skb_gro_len(p) != pinfo->gso_size) return -E2BIG; -- cgit