netdev - Re: [PATCH net-next] neigh: reorder struct neighbour fields

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Date:	Tue, 12 Oct 2010 00:20:54 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] neigh: reorder struct neighbour fields

Le mardi 12 octobre 2010 à 00:02 +0200, Eric Dumazet a écrit :
> Here is the followup patch.
> 
> Thanks !
> 

Oops, this was an old version, the up2date ones also took care of "used"
field.

I guess its time for a sleep, sorry again.


[PATCH net-next V2] neigh: reorder struct neighbour fields

(refcnt) and (ha_lock, ha, used, dev, output, ops, primary_key) should
be placed on a separate cache lines.

refcnt can be often written, while other fields are mostly read.

This gave me good result on stress test :

before:

real    0m45.570s
user    0m15.525s
sys     9m56.669s

After:

real    0m41.841s
user    0m15.261s
sys     8m45.949s

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index f04e7a2..55590ab 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -94,8 +94,6 @@ struct neighbour {
 	struct neighbour __rcu	*next;
 	struct neigh_table	*tbl;
 	struct neigh_parms	*parms;
-	struct net_device	*dev;
-	unsigned long		used;
 	unsigned long		confirmed;
 	unsigned long		updated;
 	__u8			flags;
@@ -103,16 +101,18 @@ struct neighbour {
 	__u8			type;
 	__u8			dead;
 	atomic_t		refcnt;
+	struct sk_buff_head	arp_queue;
+	struct timer_list	timer;
+	unsigned long		used;
 	atomic_t		probes;
 	rwlock_t		lock;
 	seqlock_t		ha_lock;
 	unsigned char		ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];
 	struct hh_cache		*hh;
 	int			(*output)(struct sk_buff *skb);
-	struct sk_buff_head	arp_queue;
-	struct timer_list	timer;
 	const struct neigh_ops	*ops;
 	struct rcu_head		rcu;
+	struct net_device	*dev;
 	u8			primary_key[0];
 };
 


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