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

Eric Dumazet
2010-10-11T22:21:14Z

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@gmail.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];
};