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authorEric Dumazet <dada1@cosmosbay.com>2009-05-18 00:34:33 +0000
committerDavid S. Miller <davem@davemloft.net>2009-05-18 15:15:06 -0700
commit7004bf252c53da18f6b55103e0c92f777f846806 (patch)
tree29868ce170599fbed3471f53afe3a20f23fb31c3 /include/linux/netdevice.h
parentba98898eb3fc07ee54566fcc3626354a44355acb (diff)
net: add tx_packets/tx_bytes/tx_dropped counters in struct netdev_queue
offsetof(struct net_device, features)=0x44 offsetof(struct net_device, stats.tx_packets)=0x54 offsetof(struct net_device, stats.tx_bytes)=0x5c offsetof(struct net_device, stats.tx_dropped)=0x6c Network drivers that touch dev->stats.tx_packets/stats.tx_bytes in their tx path can slow down SMP operations, since they dirty a cache line that should stay shared (dev->features is needed in rx and tx paths) We could move away stats field in net_device but it wont help that much. (Two cache lines dirtied in tx path, we can do one only) Better solution is to add tx_packets/tx_bytes/tx_dropped in struct netdev_queue because this structure is already touched in tx path and counters updates will then be free (no increase in size) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/netdevice.h')
-rw-r--r--include/linux/netdevice.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index cd547d04a8c..f8574e76b74 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -474,6 +474,9 @@ struct netdev_queue {
* please use this field instead of dev->trans_start
*/
unsigned long trans_start;
+ unsigned long tx_bytes;
+ unsigned long tx_packets;
+ unsigned long tx_dropped;
} ____cacheline_aligned_in_smp;