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authorDavid S. Miller <davem@davemloft.net>2005-07-06 00:17:25 +0200
committerDavid S. Miller <davem@davemloft.net>2005-07-06 00:17:25 +0200
commitc65f7f00c587828e3d50737805a78f74804972de (patch)
tree160f85e7d9ec1df2432b4dd3fae315812558bd10 /include
parent[NET]: Remove __ARGS from include/net/slhc_vj.h (diff)
downloadlinux-c65f7f00c587828e3d50737805a78f74804972de.tar.xz
linux-c65f7f00c587828e3d50737805a78f74804972de.zip
[TCP]: Simplify SKB data portion allocation with NETIF_F_SG.
The ideal and most optimal layout for an SKB when doing scatter-gather is to put all the headers at skb->data, and all the user data in the page array. This makes SKB splitting and combining extremely simple, especially before a packet goes onto the wire the first time. So, when sk_stream_alloc_pskb() is given a zero size, make sure there is no skb_tailroom(). This is achieved by applying SKB_DATA_ALIGN() to the header length used here. Next, make select_size() in TCP output segmentation use a length of zero when NETIF_F_SG is true on the outgoing interface. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/net/sock.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index e593af5b1ecc..7b76f891ae2d 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1134,13 +1134,16 @@ static inline void sk_stream_moderate_sndbuf(struct sock *sk)
static inline struct sk_buff *sk_stream_alloc_pskb(struct sock *sk,
int size, int mem, int gfp)
{
- struct sk_buff *skb = alloc_skb(size + sk->sk_prot->max_header, gfp);
+ struct sk_buff *skb;
+ int hdr_len;
+ hdr_len = SKB_DATA_ALIGN(sk->sk_prot->max_header);
+ skb = alloc_skb(size + hdr_len, gfp);
if (skb) {
skb->truesize += mem;
if (sk->sk_forward_alloc >= (int)skb->truesize ||
sk_stream_mem_schedule(sk, skb->truesize, 0)) {
- skb_reserve(skb, sk->sk_prot->max_header);
+ skb_reserve(skb, hdr_len);
return skb;
}
__kfree_skb(skb);