From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 11 Nov 2010 06:57:19 +0000 (+0000)
Subject: neigh: reorder struct neighbour
X-Git-Tag: upstream/snapshot3+hdmi~12141^2~600
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=46b13fc5c0f239f36e84665c73087d5fa86bfd86;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

neigh: reorder struct neighbour

It is important to move nud_state outside of the often modified cache
line (because of refcnt), to reduce false sharing in neigh_event_send()

This is a followup of commit 0ed8ddf4045f (neigh: Protect neigh->ha[]
with a seqlock)

This gives a 7% speedup on routing test with IP route cache disabled.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 55590ab..815b2ce 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -96,16 +96,16 @@ struct neighbour {
 	struct neigh_parms	*parms;
 	unsigned long		confirmed;
 	unsigned long		updated;
-	__u8			flags;
-	__u8			nud_state;
-	__u8			type;
-	__u8			dead;
+	rwlock_t		lock;
 	atomic_t		refcnt;
 	struct sk_buff_head	arp_queue;
 	struct timer_list	timer;
 	unsigned long		used;
 	atomic_t		probes;
-	rwlock_t		lock;
+	__u8			flags;
+	__u8			nud_state;
+	__u8			type;
+	__u8			dead;
 	seqlock_t		ha_lock;
 	unsigned char		ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];
 	struct hh_cache		*hh;