net 01/05: fib_rules: rearrange struct fib_rule
authorPatrick McHardy <kaber@trash.net>
Thu, 3 Dec 2009 01:25:53 +0000 (01:25 +0000)
committerDavid S. Miller <davem@davemloft.net>
Thu, 3 Dec 2009 20:14:34 +0000 (12:14 -0800)
commitd285834001df372f81045bb41092e54943e93c84
tree171c1e6c6a90874cab7cd3ed592e3688ae1cfb79
parentff236f7af82fae0818d7cbb5a0717d3218d00bdd
net 01/05: fib_rules: rearrange struct fib_rule

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>

Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/fib_rules.h