From 9356b8fc07dc126cd91d2b12f314d760ab48996e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 27 Sep 2005 15:23:16 -0700 Subject: [PATCH] [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: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/netdevice.h | 89 ++++++++++++++++++++++++--------------- 1 file changed, 55 insertions(+), 34 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 7c717907896..368e4c825ff 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -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, -- 2.41.1