Commit c6865cb3 authored Aug 14, 2011 by Tom Herbert Committed by David S. Miller Aug 17, 2011

rps: Inspect GRE encapsulated packets to get flow hash



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>

parent e971b722

net/core/dev.c

+22 −0

Original line number	Diff line number	Diff line
		@@ -2570,6 +2570,28 @@ void __skb_get_rxhash(struct sk_buff *skb)
		}

		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;
		}