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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 7f5755b..0d78e04 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1974,7 +1974,7 @@
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 @@
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 @@
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 @@
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;