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Commit 78a478d0 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
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gro: Inline skb_gro_header and cache frag0 virtual address 



The function skb_gro_header is called four times per packet which
quickly adds up at 10Gb/s.  This patch inlines it to allow better
optimisations.

Some architectures perform multiplication for page_address, which
is done by each skb_gro_header invocation.  This patch caches that
value in skb->cb to avoid the unnecessary multiplications.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 42da6994

include/linux/netdevice.h

+15 −7
Original line number Diff line number Diff line
@@ -1008,6 +1008,9 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi, 
void netif_napi_del(struct napi_struct *napi);



struct napi_gro_cb {

	/* Virtual address of skb_shinfo(skb)->frags[0].page + offset. */

	void *frag0;



	/* This indicates where we are processing relative to skb->data. */

	int data_offset;
@@ -1107,9 +1110,9 @@ extern int dev_restart(struct net_device *dev); 
#ifdef CONFIG_NETPOLL_TRAP

extern int		netpoll_trap(void);

#endif

extern void	      *skb_gro_header(struct sk_buff *skb, unsigned int hlen);

extern int	       skb_gro_receive(struct sk_buff **head,

				       struct sk_buff *skb);

extern void	       skb_gro_reset_offset(struct sk_buff *skb);



static inline unsigned int skb_gro_offset(const struct sk_buff *skb)

{
@@ -1126,23 +1129,28 @@ static inline void skb_gro_pull(struct sk_buff *skb, unsigned int len) 
	NAPI_GRO_CB(skb)->data_offset += len;

}



static inline void skb_gro_reset_offset(struct sk_buff *skb)

static inline void *skb_gro_header(struct sk_buff *skb, unsigned int hlen)

{

	NAPI_GRO_CB(skb)->data_offset = 0;

	unsigned int offset = skb_gro_offset(skb);



	hlen += offset;

	if (!NAPI_GRO_CB(skb)->frag0 ||

	    unlikely(skb_shinfo(skb)->frags[0].size + skb_headlen(skb) < hlen))

		return pskb_may_pull(skb, hlen) ? skb->data + offset : NULL;



	return NAPI_GRO_CB(skb)->frag0 + offset;

}



static inline void *skb_gro_mac_header(struct sk_buff *skb)

{

	return skb_headlen(skb) ? skb_mac_header(skb) :

	       page_address(skb_shinfo(skb)->frags[0].page) +

	       skb_shinfo(skb)->frags[0].page_offset;

	       NAPI_GRO_CB(skb)->frag0;

}



static inline void *skb_gro_network_header(struct sk_buff *skb)

{

	return skb_headlen(skb) ? skb_network_header(skb) :

	       page_address(skb_shinfo(skb)->frags[0].page) +

	       skb_shinfo(skb)->frags[0].page_offset + skb_network_offset(skb);

	       NAPI_GRO_CB(skb)->frag0 + skb_network_offset(skb);

}



static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,

net/core/dev.c

+12 −15
Original line number Diff line number Diff line
@@ -2390,21 +2390,6 @@ void napi_gro_flush(struct napi_struct *napi) 
}

EXPORT_SYMBOL(napi_gro_flush);



void *skb_gro_header(struct sk_buff *skb, unsigned int hlen)

{

	unsigned int offset = skb_gro_offset(skb);



	hlen += offset;

	if (unlikely(skb_headlen(skb) ||

		     skb_shinfo(skb)->frags[0].size < hlen ||

		     PageHighMem(skb_shinfo(skb)->frags[0].page)))

		return pskb_may_pull(skb, hlen) ? skb->data + offset : NULL;



	return page_address(skb_shinfo(skb)->frags[0].page) +

	       skb_shinfo(skb)->frags[0].page_offset + offset;

}

EXPORT_SYMBOL(skb_gro_header);



int dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)

{

	struct sk_buff **pp = NULL;
@@ -2520,6 +2505,18 @@ int napi_skb_finish(int ret, struct sk_buff *skb) 
}

EXPORT_SYMBOL(napi_skb_finish);



void skb_gro_reset_offset(struct sk_buff *skb)

{

	NAPI_GRO_CB(skb)->data_offset = 0;

	NAPI_GRO_CB(skb)->frag0 = NULL;



	if (!skb_headlen(skb) && !PageHighMem(skb_shinfo(skb)->frags[0].page))

		NAPI_GRO_CB(skb)->frag0 =

			page_address(skb_shinfo(skb)->frags[0].page) +

			skb_shinfo(skb)->frags[0].page_offset;

}

EXPORT_SYMBOL(skb_gro_reset_offset);



int napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)

{

	skb_gro_reset_offset(skb);