net 01/05: fib_rules: rearrange struct fib_rule

Patrick McHardy
2009-12-03T11:25:47Z

commit b8952893d5d86f69c4e499d191b98c6658f64b0f
Author: Patrick McHardy <kaber@trash.net>
Date: Thu Dec 3 12:05:22 2009 +0100

net: fib_rules: rearrange struct fib_rule

The ifname member is only used to resolve interface names and is not needed
during rule lookups. The target and ctarget members however are used during
rule lookups and are currently located in a second cacheline.

Move ifname further to the end to make sure both target and ctarget are
located in the same cacheline as other members used during rule lookups.

The layout on 64 bit changes from:

struct fib_rule {
...
u32 table; /* 56 4 */
u8 action; /* 60 1 */

/* XXX 3 bytes hole, try to pack */

/* --- cacheline 1 boundary (64 bytes) --- */
u32 target; /* 64 4 */

/* XXX 4 bytes hole, try to pack */

struct fib_rule * ctarget; /* 72 8 */
struct rcu_head rcu; /* 80 16 */
struct net * fr_net; /* 96 8 */
};

to:

struct fib_rule {
...
u32 table; /* 40 4 */
u8 action; /* 44 1 */

/* XXX 3 bytes hole, try to pack */

u32 target; /* 48 4 */

/* XXX 4 bytes hole, try to pack */

struct fib_rule * ctarget; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
char ifname[16]; /* 64 16 */
struct rcu_head rcu; /* 80 16 */
struct net * fr_net; /* 96 8 */

};

Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 2cd707b..22fb323 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -11,7 +11,6 @@ struct fib_rule {
struct list_head list;
atomic_t refcnt;
int ifindex;
- char ifname[IFNAMSIZ];
u32 mark;
u32 mark_mask;
u32 pref;
@@ -20,6 +19,7 @@ struct fib_rule {
u8 action;
u32 target;
struct fib_rule * ctarget;
+ char ifname[IFNAMSIZ];
struct rcu_head rcu;
struct net * fr_net;
};