diff options
author | Eric Dumazet <dada1@cosmosbay.com> | 2009-05-17 20:34:33 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2009-05-18 18:15:06 -0400 |
commit | 7004bf252c53da18f6b55103e0c92f777f846806 (patch) | |
tree | 29868ce170599fbed3471f53afe3a20f23fb31c3 /net | |
parent | ba98898eb3fc07ee54566fcc3626354a44355acb (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 'net')
-rw-r--r-- | net/core/dev.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 14dd725aaab7..6d3630d16271 100644 --- a/net/core/dev.c +++ b/net/core/dev.c | |||
@@ -4943,13 +4943,30 @@ void netdev_run_todo(void) | |||
4943 | * the internal statistics structure is used. | 4943 | * the internal statistics structure is used. |
4944 | */ | 4944 | */ |
4945 | const struct net_device_stats *dev_get_stats(struct net_device *dev) | 4945 | const struct net_device_stats *dev_get_stats(struct net_device *dev) |
4946 | { | 4946 | { |
4947 | const struct net_device_ops *ops = dev->netdev_ops; | 4947 | const struct net_device_ops *ops = dev->netdev_ops; |
4948 | 4948 | ||
4949 | if (ops->ndo_get_stats) | 4949 | if (ops->ndo_get_stats) |
4950 | return ops->ndo_get_stats(dev); | 4950 | return ops->ndo_get_stats(dev); |
4951 | else | 4951 | else { |
4952 | return &dev->stats; | 4952 | unsigned long tx_bytes = 0, tx_packets = 0, tx_dropped = 0; |
4953 | struct net_device_stats *stats = &dev->stats; | ||
4954 | unsigned int i; | ||
4955 | struct netdev_queue *txq; | ||
4956 | |||
4957 | for (i = 0; i < dev->num_tx_queues; i++) { | ||
4958 | txq = netdev_get_tx_queue(dev, i); | ||
4959 | tx_bytes += txq->tx_bytes; | ||
4960 | tx_packets += txq->tx_packets; | ||
4961 | tx_dropped += txq->tx_dropped; | ||
4962 | } | ||
4963 | if (tx_bytes || tx_packets || tx_dropped) { | ||
4964 | stats->tx_bytes = tx_bytes; | ||
4965 | stats->tx_packets = tx_packets; | ||
4966 | stats->tx_dropped = tx_dropped; | ||
4967 | } | ||
4968 | return stats; | ||
4969 | } | ||
4953 | } | 4970 | } |
4954 | EXPORT_SYMBOL(dev_get_stats); | 4971 | EXPORT_SYMBOL(dev_get_stats); |
4955 | 4972 | ||