From adc9300e78e6091a7eaa1821213836379d4dbaa8 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 17 Nov 2011 03:13:26 +0000
Subject: net: use jump_label to shortcut RPS if not setup

Most machines dont use RPS/RFS, and pay a fair amount of instructions in
netif_receive_skb() / netif_rx() / get_rps_cpu() just to discover
RPS/RFS is not setup.

Add a jump_label named rps_needed.

If no device rps_map or global rps_sock_flow_table is setup,
netif_receive_skb() / netif_rx() do a single instruction instead of many
ones, including conditional jumps.

jmp +0    (if CONFIG_JUMP_LABEL=y)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/linux/netdevice.h | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'include/linux/netdevice.h')

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4d5698aa828b..0bbe030fc014 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -214,6 +214,11 @@ enum {
 #include <linux/cache.h>
 #include <linux/skbuff.h>
 
+#ifdef CONFIG_RPS
+#include <linux/jump_label.h>
+extern struct jump_label_key rps_needed;
+#endif
+
 struct neighbour;
 struct neigh_parms;
 struct sk_buff;
-- 
cgit