Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7489594c authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

gro: Optimise length comparison in skb_gro_header 



By caching frag0_len, we can avoid checking both frag0 and the
length separately in skb_gro_header.  This helps as skb_gro_header
is called four times per packet which amounts to a few million
times at 10Gb/s.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 30a3ae30

include/linux/netdevice.h

+5 −2
Original line number Diff line number Diff line
@@ -1011,6 +1011,9 @@ struct napi_gro_cb { 
	/* Virtual address of skb_shinfo(skb)->frags[0].page + offset. */

	void *frag0;



	/* Length of frag0. */

	unsigned int frag0_len;



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

	int data_offset;
@@ -1134,9 +1137,9 @@ static inline void *skb_gro_header(struct sk_buff *skb, unsigned int hlen) 
	unsigned int offset = skb_gro_offset(skb);



	hlen += offset;

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

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

	if (NAPI_GRO_CB(skb)->frag0_len < hlen) {

		NAPI_GRO_CB(skb)->frag0 = NULL;

		NAPI_GRO_CB(skb)->frag0_len = 0;

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

	}

net/core/dev.c

+4 −1
Original line number Diff line number Diff line
@@ -2509,12 +2509,15 @@ void skb_gro_reset_offset(struct sk_buff *skb) 
{

	NAPI_GRO_CB(skb)->data_offset = 0;

	NAPI_GRO_CB(skb)->frag0 = NULL;

	NAPI_GRO_CB(skb)->frag0_len = 0;



	if (skb->mac_header == skb->tail &&

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

	    !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;

		NAPI_GRO_CB(skb)->frag0_len = skb_shinfo(skb)->frags[0].size;

	}

}

EXPORT_SYMBOL(skb_gro_reset_offset);