Group some variables based on their sizes to reduce hole and avoid padding.
On x86_64, this shrinks the size of 'struct netlbl_domaddr6_map'
from 72 to 64 bytes.
It saves a few bytes of memory and is more cache-line friendly.
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Using pahole
Before:
======
struct netlbl_dom_map {
char * domain; /* 0 8 */
u16 family; /* 8 2 */
/* XXX 6 bytes hole, try to pack */
struct netlbl_dommap_def def; /* 16 16 */
u32 valid; /* 32 4 */
/* XXX 4 bytes hole, try to pack */
struct list_head list; /* 40 16 */
struct callback_head rcu __attribute__((__aligned__(8))); /* 56 16 */
/* size: 72, cachelines: 2, members: 6 */
/* sum members: 62, holes: 2, sum holes: 10 */
/* forced alignments: 1 */
/* last cacheline: 8 bytes */
} __attribute__((__aligned__(8)));
After:
=====
struct netlbl_dom_map {
char * domain; /* 0 8 */
struct netlbl_dommap_def def; /* 8 16 */
u16 family; /* 24 2 */
/* XXX 2 bytes hole, try to pack */
u32 valid; /* 28 4 */
struct list_head list; /* 32 16 */
struct callback_head rcu __attribute__((__aligned__(8))); /* 48 16 */
/* size: 64, cachelines: 1, members: 6 */
/* sum members: 62, holes: 1, sum holes: 2 */
/* forced alignments: 1 */
} __attribute__((__aligned__(8)));
---
net/netlabel/netlabel_domainhash.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netlabel/netlabel_domainhash.h b/net/netlabel/netlabel_domainhash.h
index 9f80972ae39b..7eaa35fdd9bd 100644
--- a/net/netlabel/netlabel_domainhash.h
+++ b/net/netlabel/netlabel_domainhash.h
@@ -57,8 +57,8 @@ struct netlbl_domaddr6_map {
struct netlbl_dom_map {
char *domain;
- u16 family;
struct netlbl_dommap_def def;
+ u16 family;
u32 valid;
struct list_head list;
--
2.34.1
