[INET6]: Reorganize struct inet6_dev to save 8 bytes
authorArnaldo Carvalho de Melo <acme@redhat.com>
Sun, 3 Feb 2008 12:06:59 +0000 (04:06 -0800)
committerDavid S. Miller <davem@davemloft.net>
Sun, 3 Feb 2008 12:28:52 +0000 (04:28 -0800)
And make it a multiple of a 64 bytes, reducing cacheline trashing:

Before:

[acme@doppio net-2.6]$ pahole -C inet6_dev net/dccp/ipv6.o
struct inet6_dev {
<SNIP>
long unsigned int          mc_maxdelay;          /*    48     8 */
unsigned char              mc_qrv;               /*    56     1 */
unsigned char              mc_gq_running;        /*    57     1 */
unsigned char              mc_ifc_count;         /*    58     1 */

/* XXX 5 bytes hole, try to pack */

/* --- cacheline 1 boundary (64 bytes) --- */
struct timer_list          mc_gq_timer;          /*    64    48 */
<SNIP>
__u32                      if_flags;             /*   180     4 */
int                        dead;                 /*   184     4 */
u8                         rndid[8];             /*   188     8 */

/* XXX 4 bytes hole, try to pack */

/* --- cacheline 3 boundary (192 bytes) was 8 bytes ago --- */
struct timer_list          regen_timer;          /*   200    48 */

<SNIP>

/* size: 456, cachelines: 8 */
/* sum members: 447, holes: 2, sum holes: 9 */
/* last cacheline: 8 bytes */
};

After:

net-2.6/net/ipv6/af_inet6.c:
  struct inet6_dev |   -8
 1 struct changed

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/if_inet6.h

index b24508abb8505bff87d1ba1f139f25db0f4a10e6..66c43e29ea0a956d1eb298851c7cc41988d992af 100644 (file)
@@ -166,11 +166,11 @@ struct inet6_dev
        struct ifmcaddr6        *mc_list;
        struct ifmcaddr6        *mc_tomb;
        rwlock_t                mc_lock;
-       unsigned long           mc_v1_seen;
-       unsigned long           mc_maxdelay;
        unsigned char           mc_qrv;
        unsigned char           mc_gq_running;
        unsigned char           mc_ifc_count;
+       unsigned long           mc_v1_seen;
+       unsigned long           mc_maxdelay;
        struct timer_list       mc_gq_timer;    /* general query timer */
        struct timer_list       mc_ifc_timer;   /* interface change timer */