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rps: Inspect GRE encapsulated packets to get flow hash

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Crack open GRE packets in __skb_get_rxhash to compute 4-tuple hash on
in encapsulated packet.  Note that this is used only when the
__skb_get_rxhash is taken, in particular only when the device does
not compute provide the rxhash (ie. feature is disabled).

This was tested by creating a single GRE tunnel between two 16 core
AMD machines.  200 netperf TCP_RR streams were ran with 1 byte
request and response size.

Without patch: 157497 tps, 50/90/99% latencies 1250/1292/1364 usecs
With patch: 325896 tps, 50/90/99% latencies 603/848/1169

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Herbert 2011-08-14 19:46:29 +00:00 committed by David S. Miller
parent e971b7225b
commit c6865cb3cc
1 changed files with 22 additions and 0 deletions
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22
net/core/dev.c
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@ -2570,6 +2570,28 @@ again:
}
switch (ip_proto) {
case IPPROTO_GRE:
if (pskb_may_pull(skb, nhoff + 16)) {
u8 *h = skb->data + nhoff;
__be16 flags = *(__be16 *)h;
/*
* Only look inside GRE if version zero and no
* routing
*/
if (!(flags & (GRE_VERSION|GRE_ROUTING))) {
proto = *(__be16 *)(h + 2);
nhoff += 4;
if (flags & GRE_CSUM)
nhoff += 4;
if (flags & GRE_KEY)
nhoff += 4;
if (flags & GRE_SEQ)
nhoff += 4;
goto again;
}
}
break;
default:
break;
}