gro: Optimise Ethernet header comparison
This patch optimises the Ethernet header comparison to use 2-byte and 4-byte xors instead of memcmp. In order to facilitate this, the actual comparison is now carried out by the callers of the shared dev_gro_receive function. This has a significant impact when receiving 1500B packets through 10GbE. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -184,4 +184,25 @@ static inline unsigned compare_ether_addr_64bits(const u8 addr1[6+2],
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}
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#endif /* __KERNEL__ */
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/**
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* compare_ether_header - Compare two Ethernet headers
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* @a: Pointer to Ethernet header
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* @b: Pointer to Ethernet header
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*
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* Compare two ethernet headers, returns 0 if equal.
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* This assumes that the network header (i.e., IP header) is 4-byte
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* aligned OR the platform can handle unaligned access. This is the
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* case for all packets coming into netif_receive_skb or similar
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* entry points.
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*/
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static inline int compare_ether_header(const void *a, const void *b)
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{
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u32 *a32 = (u32 *)((u8 *)a + 2);
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u32 *b32 = (u32 *)((u8 *)b + 2);
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return (*(u16 *)a ^ *(u16 *)b) | (a32[0] ^ b32[0]) |
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(a32[1] ^ b32[1]) | (a32[2] ^ b32[2]);
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}
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#endif /* _LINUX_ETHERDEVICE_H */
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@ -1117,6 +1117,13 @@ static inline void skb_gro_reset_offset(struct sk_buff *skb)
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NAPI_GRO_CB(skb)->data_offset = 0;
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}
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static inline void *skb_gro_mac_header(struct sk_buff *skb)
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{
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return skb_mac_header(skb) < skb->data ? skb_mac_header(skb) :
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page_address(skb_shinfo(skb)->frags[0].page) +
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skb_shinfo(skb)->frags[0].page_offset;
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}
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static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
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unsigned short type,
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const void *daddr, const void *saddr,
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@ -85,7 +85,9 @@ static int vlan_gro_common(struct napi_struct *napi, struct vlan_group *grp,
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goto drop;
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for (p = napi->gro_list; p; p = p->next) {
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NAPI_GRO_CB(p)->same_flow = p->dev == skb->dev;
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NAPI_GRO_CB(p)->same_flow =
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p->dev == skb->dev && !compare_ether_header(
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skb_mac_header(p), skb_gro_mac_header(skb));
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NAPI_GRO_CB(p)->flush = 0;
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}
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@ -215,13 +215,6 @@ static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
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return &net->dev_index_head[ifindex & ((1 << NETDEV_HASHBITS) - 1)];
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}
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static inline void *skb_gro_mac_header(struct sk_buff *skb)
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{
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return skb_mac_header(skb) < skb->data ? skb_mac_header(skb) :
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page_address(skb_shinfo(skb)->frags[0].page) +
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skb_shinfo(skb)->frags[0].page_offset;
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}
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/* Device list insertion */
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static int list_netdevice(struct net_device *dev)
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{
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@ -2415,29 +2408,16 @@ int dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
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rcu_read_lock();
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list_for_each_entry_rcu(ptype, head, list) {
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struct sk_buff *p;
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void *mac;
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if (ptype->type != type || ptype->dev || !ptype->gro_receive)
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continue;
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skb_set_network_header(skb, skb_gro_offset(skb));
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mac = skb_gro_mac_header(skb);
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mac_len = skb->network_header - skb->mac_header;
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skb->mac_len = mac_len;
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NAPI_GRO_CB(skb)->same_flow = 0;
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NAPI_GRO_CB(skb)->flush = 0;
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NAPI_GRO_CB(skb)->free = 0;
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for (p = napi->gro_list; p; p = p->next) {
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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if (p->mac_len != mac_len ||
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memcmp(skb_mac_header(p), mac, mac_len))
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NAPI_GRO_CB(p)->same_flow = 0;
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}
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pp = ptype->gro_receive(&napi->gro_list, skb);
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break;
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}
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@ -2492,7 +2472,8 @@ static int __napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
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struct sk_buff *p;
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for (p = napi->gro_list; p; p = p->next) {
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NAPI_GRO_CB(p)->same_flow = 1;
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NAPI_GRO_CB(p)->same_flow = !compare_ether_header(
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skb_mac_header(p), skb_gro_mac_header(skb));
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NAPI_GRO_CB(p)->flush = 0;
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}
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