diff options
| author | Eric Dumazet <dada1@cosmosbay.com> | 2009-04-28 04:43:42 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-04-28 04:43:42 -0700 |
| commit | 6a321cb370ad3db4ba6e405e638b3a42c41089b0 (patch) | |
| tree | 2e7c25cff76fc6b439afb04e24ab1133e42667b8 /include | |
| parent | 8555a5948467e941acc34e8b1c30df4c1f2f5862 (diff) | |
net: netif_tx_queue_stopped too expensive
netif_tx_queue_stopped(txq) is most of the time false.
Yet its cost is very expensive on SMP.
static inline int netif_tx_queue_stopped(const struct netdev_queue *dev_queue)
{
return test_bit(__QUEUE_STATE_XOFF, &dev_queue->state);
}
I saw this on oprofile hunting and bnx2 driver bnx2_tx_int().
We probably should split "struct netdev_queue" in two parts, one
being read mostly.
__netif_tx_lock() touches _xmit_lock & xmit_lock_owner, these
deserve a separate cache line.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/netdevice.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index f8c3619d551..505a3c6cb12 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -447,12 +447,18 @@ enum netdev_queue_state_t }; struct netdev_queue { +/* + * read mostly part + */ struct net_device *dev; struct Qdisc *qdisc; unsigned long state; - spinlock_t _xmit_lock; - int xmit_lock_owner; struct Qdisc *qdisc_sleeping; +/* + * write mostly part + */ + spinlock_t _xmit_lock ____cacheline_aligned_in_smp; + int xmit_lock_owner; } ____cacheline_aligned_in_smp; |