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: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d1afc3b..2e44a04 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1011,6 +1011,9 @@
/* 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 @@
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;
}
diff --git a/net/core/dev.c b/net/core/dev.c
index f9d90c5..b1722a2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2509,12 +2509,15 @@
{
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);