Commit 9356b8fc authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

[NET]: Reorder some hot fields of struct net_device 



Place them on separate cache lines in SMP to lower memory bouncing
between multiple CPU accessing the device.

     - One part is mostly used on receive path (including
       eth_type_trans()) (poll_list, poll, quota, weight, last_rx,
       dev_addr, broadcast)

     - One part is mostly used on queue transmit path (qdisc)
      (queue_lock, qdisc, qdisc_sleeping, qdisc_list, tx_queue_len)

     - One part is mostly used on xmit path (device)
      (xmit_lock, xmit_lock_owner, priv, hard_start_xmit, trans_start)

'features' is placed outside of these hot points, in a location that
may be shared by all cpus (because mostly read)

name_hlist is moved close to name[IFNAMSIZ] to speedup __dev_get_by_name()

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2d7ceece

include/linux/netdevice.h

+55 −34
Original line number Diff line number Diff line
@@ -265,6 +265,8 @@ struct net_device 
	 * the interface.

	 */

	char			name[IFNAMSIZ];

	/* device name hash chain */

	struct hlist_node	name_hlist;



	/*

	 *	I/O specific fields
@@ -292,6 +294,21 @@ struct net_device 


	/* ------- Fields preinitialized in Space.c finish here ------- */



	/* Net device features */

	unsigned long		features;

#define NETIF_F_SG		1	/* Scatter/gather IO. */

#define NETIF_F_IP_CSUM		2	/* Can checksum only TCP/UDP over IPv4. */

#define NETIF_F_NO_CSUM		4	/* Does not require checksum. F.e. loopack. */

#define NETIF_F_HW_CSUM		8	/* Can checksum all the packets. */

#define NETIF_F_HIGHDMA		32	/* Can DMA to high memory. */

#define NETIF_F_FRAGLIST	64	/* Scatter/gather IO. */

#define NETIF_F_HW_VLAN_TX	128	/* Transmit VLAN hw acceleration */

#define NETIF_F_HW_VLAN_RX	256	/* Receive VLAN hw acceleration */

#define NETIF_F_HW_VLAN_FILTER	512	/* Receive filtering on VLAN */

#define NETIF_F_VLAN_CHALLENGED	1024	/* Device cannot handle VLAN packets */

#define NETIF_F_TSO		2048	/* Can offload TCP/IP segmentation */

#define NETIF_F_LLTX		4096	/* LockLess TX */



	struct net_device	*next_sched;



	/* Interface index. Unique device identifier	*/
@@ -316,9 +333,6 @@ struct net_device 
	 * will (read: may be cleaned up at will).

	 */



	/* These may be needed for future network-power-down code. */

	unsigned long		trans_start;	/* Time (in jiffies) of last Tx	*/

	unsigned long		last_rx;	/* Time of last Rx	*/



	unsigned short		flags;	/* interface flags (a la BSD)	*/

	unsigned short		gflags;
@@ -328,15 +342,12 @@ struct net_device 
	unsigned		mtu;	/* interface MTU value		*/

	unsigned short		type;	/* interface hardware type	*/

	unsigned short		hard_header_len;	/* hardware hdr length	*/

	void			*priv;	/* pointer to private data	*/



	struct net_device	*master; /* Pointer to master device of a group,

					  * which this device is member of.

					  */



	/* Interface address info. */

	unsigned char		broadcast[MAX_ADDR_LEN];	/* hw bcast add	*/

	unsigned char		dev_addr[MAX_ADDR_LEN];	/* hw address	*/

	unsigned char		perm_addr[MAX_ADDR_LEN]; /* permanent hw address */

	unsigned char		addr_len;	/* hardware address length	*/

	unsigned short          dev_id;		/* for shared network cards */
@@ -346,8 +357,6 @@ struct net_device 
	int			promiscuity;

	int			allmulti;



	int			watchdog_timeo;

	struct timer_list	watchdog_timer;



	/* Protocol specific pointers */
@@ -358,32 +367,62 @@ struct net_device 
	void			*ec_ptr;	/* Econet specific data	*/

	void			*ax25_ptr;	/* AX.25 specific data */



	struct list_head	poll_list;	/* Link to poll list	*/

/*

 * Cache line mostly used on receive path (including eth_type_trans())

 */

	struct list_head	poll_list ____cacheline_aligned_in_smp;

					/* Link to poll list	*/



	int			(*poll) (struct net_device *dev, int *quota);

	int			quota;

	int			weight;

	unsigned long		last_rx;	/* Time of last Rx	*/

	/* Interface address info used in eth_type_trans() */

	unsigned char		dev_addr[MAX_ADDR_LEN];	/* hw address, (before bcast 

							because most packets are unicast) */



	unsigned char		broadcast[MAX_ADDR_LEN];	/* hw bcast add	*/



/*

 * Cache line mostly used on queue transmit path (qdisc)

 */

	/* device queue lock */

	spinlock_t		queue_lock ____cacheline_aligned_in_smp;

	struct Qdisc		*qdisc;

	struct Qdisc		*qdisc_sleeping;

	struct Qdisc		*qdisc_ingress;

	struct list_head	qdisc_list;

	unsigned long		tx_queue_len;	/* Max frames per queue allowed */



	/* ingress path synchronizer */

	spinlock_t		ingress_lock;

	struct Qdisc		*qdisc_ingress;



/*

 * One part is mostly used on xmit path (device)

 */

	/* hard_start_xmit synchronizer */

	spinlock_t		xmit_lock;

	spinlock_t		xmit_lock ____cacheline_aligned_in_smp;

	/* cpu id of processor entered to hard_start_xmit or -1,

	   if nobody entered there.

	 */

	int			xmit_lock_owner;

	/* device queue lock */

	spinlock_t		queue_lock;

	void			*priv;	/* pointer to private data	*/

	int			(*hard_start_xmit) (struct sk_buff *skb,

						    struct net_device *dev);

	/* These may be needed for future network-power-down code. */

	unsigned long		trans_start;	/* Time (in jiffies) of last Tx	*/



	int			watchdog_timeo; /* used by dev_watchdog() */

	struct timer_list	watchdog_timer;



/*

 * refcnt is a very hot point, so align it on SMP

 */

	/* Number of references to this device */

	atomic_t		refcnt;

	atomic_t		refcnt ____cacheline_aligned_in_smp;



	/* delayed register/unregister */

	struct list_head	todo_list;

	/* device name hash chain */

	struct hlist_node	name_hlist;

	/* device index hash chain */

	struct hlist_node	index_hlist;
@@ -396,21 +435,6 @@ struct net_device 
	       NETREG_RELEASED,		/* called free_netdev */

	} reg_state;



	/* Net device features */

	unsigned long		features;

#define NETIF_F_SG		1	/* Scatter/gather IO. */

#define NETIF_F_IP_CSUM		2	/* Can checksum only TCP/UDP over IPv4. */

#define NETIF_F_NO_CSUM		4	/* Does not require checksum. F.e. loopack. */

#define NETIF_F_HW_CSUM		8	/* Can checksum all the packets. */

#define NETIF_F_HIGHDMA		32	/* Can DMA to high memory. */

#define NETIF_F_FRAGLIST	64	/* Scatter/gather IO. */

#define NETIF_F_HW_VLAN_TX	128	/* Transmit VLAN hw acceleration */

#define NETIF_F_HW_VLAN_RX	256	/* Receive VLAN hw acceleration */

#define NETIF_F_HW_VLAN_FILTER	512	/* Receive filtering on VLAN */

#define NETIF_F_VLAN_CHALLENGED	1024	/* Device cannot handle VLAN packets */

#define NETIF_F_TSO		2048	/* Can offload TCP/IP segmentation */

#define NETIF_F_LLTX		4096	/* LockLess TX */



	/* Called after device is detached from network. */

	void			(*uninit)(struct net_device *dev);

	/* Called after last user reference disappears. */
@@ -419,10 +443,7 @@ struct net_device 
	/* Pointers to interface service routines.	*/

	int			(*open)(struct net_device *dev);

	int			(*stop)(struct net_device *dev);

	int			(*hard_start_xmit) (struct sk_buff *skb,

						    struct net_device *dev);

#define HAVE_NETDEV_POLL

	int			(*poll) (struct net_device *dev, int *quota);

	int			(*hard_header) (struct sk_buff *skb,

						struct net_device *dev,

						unsigned short type,

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