From 40d0802b3eb47d57e2d57a5244a18cbbe9632e13 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 26 Aug 2010 22:03:08 -0700 Subject: [PATCH] gro: __napi_gro_receive() optimizations compare_ether_header() can have a special implementation on 64 bit arches if CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is defined. __napi_gro_receive() and vlan_gro_common() can avoid a conditional branch to perform device match. On x86_64, __napi_gro_receive() has now 38 instructions instead of 53 As gcc-4.4.3 still choose to not inline it, add inline keyword to this performance critical function. Signed-off-by: Eric Dumazet CC: Herbert Xu Signed-off-by: David S. Miller --- include/linux/etherdevice.h | 18 +++++++++++++++++- net/8021q/vlan_core.c | 9 ++++++--- net/core/dev.c | 10 ++++++---- 3 files changed, 29 insertions(+), 8 deletions(-) diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h index 2308fbb4523a..fb6aa6070921 100644 --- a/include/linux/etherdevice.h +++ b/include/linux/etherdevice.h @@ -237,13 +237,29 @@ static inline bool is_etherdev_addr(const struct net_device *dev, * entry points. */ -static inline int compare_ether_header(const void *a, const void *b) +static inline unsigned long compare_ether_header(const void *a, const void *b) { +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 + unsigned long fold; + + /* + * We want to compare 14 bytes: + * [a0 ... a13] ^ [b0 ... b13] + * Use two long XOR, ORed together, with an overlap of two bytes. + * [a0 a1 a2 a3 a4 a5 a6 a7 ] ^ [b0 b1 b2 b3 b4 b5 b6 b7 ] | + * [a6 a7 a8 a9 a10 a11 a12 a13] ^ [b6 b7 b8 b9 b10 b11 b12 b13] + * This means the [a6 a7] ^ [b6 b7] part is done two times. + */ + fold = *(unsigned long *)a ^ *(unsigned long *)b; + fold |= *(unsigned long *)(a + 6) ^ *(unsigned long *)(b + 6); + return fold; +#else u32 *a32 = (u32 *)((u8 *)a + 2); u32 *b32 = (u32 *)((u8 *)b + 2); return (*(u16 *)a ^ *(u16 *)b) | (a32[0] ^ b32[0]) | (a32[1] ^ b32[1]) | (a32[2] ^ b32[2]); +#endif } #endif /* _LINUX_ETHERDEVICE_H */ diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c index 07eeb5b99dce..3438c01bbacf 100644 --- a/net/8021q/vlan_core.c +++ b/net/8021q/vlan_core.c @@ -105,9 +105,12 @@ vlan_gro_common(struct napi_struct *napi, struct vlan_group *grp, goto drop; for (p = napi->gro_list; p; p = p->next) { - NAPI_GRO_CB(p)->same_flow = - p->dev == skb->dev && !compare_ether_header( - skb_mac_header(p), skb_gro_mac_header(skb)); + unsigned long diffs; + + diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev; + diffs |= compare_ether_header(skb_mac_header(p), + skb_gro_mac_header(skb)); + NAPI_GRO_CB(p)->same_flow = !diffs; NAPI_GRO_CB(p)->flush = 0; } diff --git a/net/core/dev.c b/net/core/dev.c index 859e30ff044a..63bd20a75929 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3169,16 +3169,18 @@ normal: } EXPORT_SYMBOL(dev_gro_receive); -static gro_result_t +static inline gro_result_t __napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb) { struct sk_buff *p; for (p = napi->gro_list; p; p = p->next) { - NAPI_GRO_CB(p)->same_flow = - (p->dev == skb->dev) && - !compare_ether_header(skb_mac_header(p), + unsigned long diffs; + + diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev; + diffs |= compare_ether_header(skb_mac_header(p), skb_gro_mac_header(skb)); + NAPI_GRO_CB(p)->same_flow = !diffs; NAPI_GRO_CB(p)->flush = 0; } -- 2.20.1