| Message ID | aa109847260e51e174c823b6d1441f75be370f01.1687083361.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f0d952646bcf186d6d1bea6ec89f96b7e57f3b83 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] netlabel: Reorder fields in 'struct netlbl_domaddr6_map' | expand |
On Sun, Jun 18, 2023 at 12:16:41PM +0200, Christophe JAILLET wrote: > 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@wanadoo.fr> Reviewed-by: Simon Horman <simon.horman@corigine.com>
Sun, Jun 18, 2023 at 12:16:41PM CEST, christophe.jaillet@wanadoo.fr wrote: >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@wanadoo.fr> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
On Sun, Jun 18, 2023 at 6:16 AM Christophe JAILLET <christophe.jaillet@wanadoo.fr> wrote: > > 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@wanadoo.fr> > --- > 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(-) Acked-by: Paul Moore <paul@paul-moore.com>
Hello: This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <kuba@kernel.org>: On Sun, 18 Jun 2023 12:16:41 +0200 you wrote: > 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@wanadoo.fr> > > [...] Here is the summary with links: - [net-next] netlabel: Reorder fields in 'struct netlbl_domaddr6_map' https://git.kernel.org/netdev/net-next/c/f0d952646bcf You are awesome, thank you!
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;
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@wanadoo.fr> --- 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(-)