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>

1 files changed, 11 insertions, 13 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index a4a7c36917d1..4d43f1a80f74 100644
--- 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;