[PATCH net-next] netdevice.h: Align struct netdevices members

Subsystems: networking drivers, networking [general], the rest

STALE5597d

7 messages, 3 authors, 2011-05-13 · open the first message on its own page

[PATCH net-next] netdevice.h: Align struct netdevices members

From: Joe Perches <joe@perches.com>
Date: 2011-05-10 03:42:47

Save a bit of space.

Signed-off-by: Joe Perches <joe@perches.com>
---
 include/linux/netdevice.h |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d5de66a..0fcb86b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1020,9 +1020,6 @@ struct net_device {
 	 *	part of the usual set specified in Space.c.
 	 */
 
-	unsigned char		if_port;	/* Selectable AUI, TP,..*/
-	unsigned char		dma;		/* DMA channel		*/
-
 	unsigned long		state;
 
 	struct list_head	dev_list;
@@ -1141,13 +1138,16 @@ struct net_device {
 	const struct header_ops *header_ops;
 
 	unsigned int		flags;	/* interface flags (a la BSD)	*/
+	unsigned int		priv_flags; /* Like 'flags' but invisible to userspace. */
 	unsigned short		gflags;
-        unsigned int            priv_flags; /* Like 'flags' but invisible to userspace. */
 	unsigned short		padded;	/* How much padding added by alloc_netdev() */
 
 	unsigned char		operstate; /* RFC2863 operstate */
 	unsigned char		link_mode; /* mapping policy to operstate */
 
+	unsigned char		if_port;	/* Selectable AUI, TP,..*/
+	unsigned char		dma;		/* DMA channel		*/
+
 	unsigned int		mtu;	/* interface MTU value		*/
 	unsigned short		type;	/* interface hardware type	*/
 	unsigned short		hard_header_len;	/* hardware hdr length	*/

Re: [PATCH net-next] netdevice.h: Align struct netdevices members

From: Eric Dumazet <hidden>
Date: 2011-05-10 03:53:20

Le lundi 09 mai 2011 à 20:42 -0700, Joe Perches a écrit :
Save a bit of space.

Signed-off-by: Joe Perches <joe@perches.com>
---
 include/linux/netdevice.h |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
Hmm... correct alignements are far more important for this structure.

Did you run benchmarks on 32bit and 64bit platforms ?

BTW we have ____cacheline_aligned_in_smp markers, I am not even sure
this patch saves space.
quoted hunk
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d5de66a..0fcb86b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1020,9 +1020,6 @@ struct net_device {
 	 *	part of the usual set specified in Space.c.
 	 */
 
-	unsigned char		if_port;	/* Selectable AUI, TP,..*/
-	unsigned char		dma;		/* DMA channel		*/
-
 	unsigned long		state;
 
 	struct list_head	dev_list;
@@ -1141,13 +1138,16 @@ struct net_device {
 	const struct header_ops *header_ops;
 
 	unsigned int		flags;	/* interface flags (a la BSD)	*/
+	unsigned int		priv_flags; /* Like 'flags' but invisible to userspace. */
 	unsigned short		gflags;
-        unsigned int            priv_flags; /* Like 'flags' but invisible to userspace. */
 	unsigned short		padded;	/* How much padding added by alloc_netdev() */
 
 	unsigned char		operstate; /* RFC2863 operstate */
 	unsigned char		link_mode; /* mapping policy to operstate */
 
+	unsigned char		if_port;	/* Selectable AUI, TP,..*/
+	unsigned char		dma;		/* DMA channel		*/
+
 	unsigned int		mtu;	/* interface MTU value		*/
 	unsigned short		type;	/* interface hardware type	*/
 	unsigned short		hard_header_len;	/* hardware hdr length	*/

Re: [PATCH net-next] netdevice.h: Align struct netdevices members

From: Joe Perches <joe@perches.com>
Date: 2011-05-10 04:22:06

On Tue, 2011-05-10 at 05:53 +0200, Eric Dumazet wrote:
Le lundi 09 mai 2011 à 20:42 -0700, Joe Perches a écrit :
quoted
Save a bit of space.
Hmm... correct alignements are far more important for this structure.
I agree.  I aligned these members on "natural" boundaries.
4 consecutive chars rather than 2 chars, unsigned long.
 
Did you run benchmarks on 32bit and 64bit platforms ?
Nope.
BTW we have ____cacheline_aligned_in_smp markers, I am not even sure
this patch saves space.
That depends on whether or not CONFIG_SMP is defined and
all of the changes are before any ____cacheline_aligned markers.

Re: [PATCH net-next] netdevice.h: Align struct netdevices members

From: David Miller <davem@davemloft.net>
Date: 2011-05-12 22:06:11

From: Joe Perches <joe@perches.com>
Date: Mon, 09 May 2011 21:22:05 -0700
On Tue, 2011-05-10 at 05:53 +0200, Eric Dumazet wrote:
quoted
Le lundi 09 mai 2011 à 20:42 -0700, Joe Perches a écrit :
quoted
Save a bit of space.
Hmm... correct alignements are far more important for this structure.
I agree.  I aligned these members on "natural" boundaries.
4 consecutive chars rather than 2 chars, unsigned long.
 
quoted
Did you run benchmarks on 32bit and 64bit platforms ?
Nope.
quoted
BTW we have ____cacheline_aligned_in_smp markers, I am not even sure
this patch saves space.
That depends on whether or not CONFIG_SMP is defined and
all of the changes are before any ____cacheline_aligned markers.
I think this is sane, Eric do you still have objections?

Re: [PATCH net-next] netdevice.h: Align struct netdevices members

From: Joe Perches <joe@perches.com>
Date: 2011-05-12 23:49:47

On Thu, 2011-05-12 at 15:05 -0700, David Miller wrote:
I think this is sane, Eric do you still have objections?
Hey David.

If you apply this, can you please correct the
subject line typo from netdevices to net_device?

Thanks, Joe

Re: [PATCH net-next] netdevice.h: Align struct netdevices members

From: Eric Dumazet <hidden>
Date: 2011-05-13 17:47:34

Le jeudi 12 mai 2011 à 15:05 -0700, David Miller a écrit :
I think this is sane, Eric do you still have objections?
No objection, thanks

Re: [PATCH net-next] netdevice.h: Align struct netdevices members

From: David Miller <davem@davemloft.net>
Date: 2011-05-13 18:08:20

From: Joe Perches <joe@perches.com>
Date: Mon, 09 May 2011 20:42:46 -0700
Save a bit of space.

Signed-off-by: Joe Perches <joe@perches.com>
Applied with "sed 's/netdevices/net_device/" in Subject as
requested.

Thanks.
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