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net: Check skb->rxhash in gro_receive

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When initializing a gro_list for a packet, first check the rxhash of
the incoming skb against that of the skb's in the list. This should be
a very strong inidicator of whether the flow is going to be matched,
and potentially allows a lot of other checks to be short circuited.
Use skb_hash_raw so that we don't force the hash to be calculated.

Tested by running netperf 200 TCP_STREAMs between two machines with
GRO, HW rxhash, and 1G. Saw no performance degration, slight reduction
of time in dev_gro_receive.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Herbert 2014-01-15 08:58:06 -08:00 committed by David S. Miller
parent 57bdf7f42b
commit 0b4cec8c2e
1 changed files with 8 additions and 1 deletions
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9
net/core/dev.c
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@ -3821,10 +3821,18 @@ static void gro_list_prepare(struct napi_struct *napi, struct sk_buff *skb)
{
struct sk_buff *p;
unsigned int maclen = skb->dev->hard_header_len;
u32 hash = skb_get_hash_raw(skb);
for (p = napi->gro_list; p; p = p->next) {
unsigned long diffs;
NAPI_GRO_CB(p)->flush = 0;
if (hash != skb_get_hash_raw(p)) {
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
diffs |= p->vlan_tci ^ skb->vlan_tci;
if (maclen == ETH_HLEN)
@ -3835,7 +3843,6 @@ static void gro_list_prepare(struct napi_struct *napi, struct sk_buff *skb)
skb_gro_mac_header(skb),
maclen);
NAPI_GRO_CB(p)->same_flow = !diffs;
NAPI_GRO_CB(p)->flush = 0;
}
}