rps: optimize rps_get_cpu()

optimize rps_get_cpu().

don't initialize ports when we can get the ports. one memory access
for ports than two.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index a4a7c36917d1c620d1309c5f4add7f37834fe41d..4d43f1a80f740a333b926523a6a615db819ba5b8 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2229,7 +2229,11 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
        int cpu = -1;
        u8 ip_proto;
        u16 tcpu;
-       u32 addr1, addr2, ports, ihl;
+       u32 addr1, addr2, ihl;
+       union {
+               u32 v32;
+               u16 v16[2];
+       } ports;
 
        if (skb_rx_queue_recorded(skb)) {
                u16 index = skb_get_rx_queue(skb);
@@ -2275,7 +2279,6 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
        default:
                goto done;
        }
-       ports = 0;
        switch (ip_proto) {
        case IPPROTO_TCP:
        case IPPROTO_UDP:
@@ -2285,25 +2288,20 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
        case IPPROTO_SCTP:
        case IPPROTO_UDPLITE:
                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;
+                       ports.v32 = * (__force u32 *) (skb->data + (ihl * 4));
+                       if (ports.v16[1] < ports.v16[0])
+                               swap(ports.v16[0], ports.v16[1]);
+                       break;
                }
-               break;
-
        default:
+               ports.v32 = 0;
                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);
+       skb->rxhash = jhash_3words(addr1, addr2, ports.v32, hashrnd);
        if (!skb->rxhash)
                skb->rxhash = 1;