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Commit b249dcb8 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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rps: consistent rxhash 



In case we compute a software skb->rxhash, we can generate a consistent
hash : Its value will be the same in both flow directions.

This helps some workloads, like conntracking, since the same state needs
to be accessed in both directions.

tbench + RFS + this patch gives better results than tbench with default
kernel configuration (no RPS, no RFS)

Also fixed some sparse warnings.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e36fa2f7

net/core/dev.c

+18 −7
Original line number Diff line number Diff line
@@ -1974,7 +1974,7 @@ u16 skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb) 
	if (skb->sk && skb->sk->sk_hash)

		hash = skb->sk->sk_hash;

	else

		hash = skb->protocol;

		hash = (__force u16) skb->protocol;



	hash = jhash_1word(hash, hashrnd);
@@ -2253,8 +2253,8 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb, 


		ip = (struct iphdr *) skb->data;

		ip_proto = ip->protocol;

		addr1 = ip->saddr;

		addr2 = ip->daddr;

		addr1 = (__force u32) ip->saddr;

		addr2 = (__force u32) ip->daddr;

		ihl = ip->ihl;

		break;

	case __constant_htons(ETH_P_IPV6):
@@ -2263,8 +2263,8 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb, 


		ip6 = (struct ipv6hdr *) skb->data;

		ip_proto = ip6->nexthdr;

		addr1 = ip6->saddr.s6_addr32[3];

		addr2 = ip6->daddr.s6_addr32[3];

		addr1 = (__force u32) ip6->saddr.s6_addr32[3];

		addr2 = (__force u32) ip6->daddr.s6_addr32[3];

		ihl = (40 >> 2);

		break;

	default:
@@ -2279,14 +2279,25 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb, 
	case IPPROTO_AH:

	case IPPROTO_SCTP:

	case IPPROTO_UDPLITE:

		if (pskb_may_pull(skb, (ihl * 4) + 4))

			ports = *((u32 *) (skb->data + (ihl * 4)));

		if (pskb_may_pull(skb, (ihl * 4) + 4)) {

			__be16 *hports = (__be16 *) (skb->data + (ihl * 4));

			u32 sport, dport;



			sport = (__force u16) hports[0];

			dport = (__force u16) hports[1];

			if (dport < sport)

				swap(sport, dport);

			ports = (sport << 16) + dport;

		}

		break;



	default:

		break;

	}



	/* get a consistent hash (same value on both flow directions) */

	if (addr2 < addr1)

		swap(addr1, addr2);

	skb->rxhash = jhash_3words(addr1, addr2, ports, hashrnd);

	if (!skb->rxhash)

		skb->rxhash = 1;