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net: shrinks struct net_device 

commit ab95bfe01 (net: replace hooks in __netif_receive_skb) added
rx_handler at wrong place, between two cache line aligned objects,
creating a big hole (a full cache line)

Move rx_handler and rx_handler_data before rx_queue, filling existing
hole.

Move master field in the cache line(s) used in receive path.

This saves 64 bytes (or L1_CACHE_BYTES), and avoids two possible
cache misses in receive path.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-09-16 02:58:13 +00:00 committed by David S. Miller
parent 9476763262
commit cd13539b8b
1 changed files with 11 additions and 9 deletions
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20
include/linux/netdevice.h
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@ -918,10 +918,6 @@ struct net_device {
unsigned short needed_headroom;
unsigned short needed_tailroom;
struct net_device *master; /* Pointer to master device of a group,
* which this device is member of.
*/
/* Interface address info. */
unsigned char perm_addr[MAX_ADDR_LEN]; /* permanent hw address */
unsigned char addr_assign_type; /* hw address assignment type */
@ -951,7 +947,7 @@ struct net_device {
assign before registering */
/*
* Cache line mostly used on receive path (including eth_type_trans())
* Cache lines mostly used on receive path (including eth_type_trans())
*/
unsigned long last_rx; /* Time of last Rx
* This should not be set in
@ -961,6 +957,10 @@ struct net_device {
* avoid dirtying this cache line.
*/
struct net_device *master; /* Pointer to master device of a group,
* which this device is member of.
*/
/* Interface address info used in eth_type_trans() */
unsigned char *dev_addr; /* hw address, (before bcast
because most packets are
@ -980,10 +980,14 @@ struct net_device {
unsigned int num_rx_queues;
#endif
struct netdev_queue rx_queue;
rx_handler_func_t *rx_handler;
void *rx_handler_data;
struct netdev_queue rx_queue; /* use two cache lines */
/*
* Cache lines mostly used on transmit path
*/
struct netdev_queue *_tx ____cacheline_aligned_in_smp;
/* Number of TX queues allocated at alloc_netdev_mq() time */
@ -997,9 +1001,7 @@ struct net_device {
unsigned long tx_queue_len; /* Max frames per queue allowed */
spinlock_t tx_global_lock;
/*
* One part is mostly used on xmit path (device)
*/
/* These may be needed for future network-power-down code. */
/*