bond_start_xmit() spends some cycles in is_netpoll_tx_blocked(): if (unlikely(is_netpoll_tx_blocked(dev))) return NETDEV_TX_BUSY; because of the "pushf;pop reg" sequence (aka irqs_disabled()). Let's swap the conditions in is_netpoll_tx_blocked() and convert netpoll_block_tx to a static key. Before: 1.23 │ mov %gs:0x28,%rax 1.24 │ mov %rax,0x18(%rsp) 29.45 │ pushfq 0.50 │ pop %rax 0.47 │ test $0x200,%eax │ ↓ je 1b4 0.49 │ 32: lea 0x980(%rsi),%rbx After: 0.72 │ mov %gs:0x28,%rax 0.81 │ mov %rax,0x18(%rsp) 0.82 │ nop 2.77 │ 2a: lea 0x980(%rsi),%rbx Suggested-by: Eric Dumazet Signed-off-by: Kuniyuki Iwashima --- drivers/net/bonding/bond_main.c | 4 ++-- include/net/bonding.h | 10 +++++----- 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 55a960da42b5..2f2dddcf9d30 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -206,7 +206,7 @@ MODULE_PARM_DESC(lp_interval, "The number of seconds between instances where " /*----------------------------- Global variables ----------------------------*/ #ifdef CONFIG_NET_POLL_CONTROLLER -atomic_t netpoll_block_tx = ATOMIC_INIT(0); +DEFINE_STATIC_KEY_FALSE(netpoll_block_tx); #endif unsigned int bond_net_id __read_mostly; @@ -6589,7 +6589,7 @@ static void __exit bonding_exit(void) #ifdef CONFIG_NET_POLL_CONTROLLER /* Make sure we don't have an imbalance on our netpoll blocking */ - WARN_ON(atomic_read(&netpoll_block_tx)); + WARN_ON(static_branch_unlikely(&netpoll_block_tx)); #endif } diff --git a/include/net/bonding.h b/include/net/bonding.h index 4ad5521e7731..7f8fda2fdfcb 100644 --- a/include/net/bonding.h +++ b/include/net/bonding.h @@ -91,22 +91,22 @@ NETIF_F_GSO_ESP) #ifdef CONFIG_NET_POLL_CONTROLLER -extern atomic_t netpoll_block_tx; +DECLARE_STATIC_KEY_FALSE(netpoll_block_tx); static inline void block_netpoll_tx(void) { - atomic_inc(&netpoll_block_tx); + static_branch_inc(&netpoll_block_tx); } static inline void unblock_netpoll_tx(void) { - atomic_dec(&netpoll_block_tx); + static_branch_dec(&netpoll_block_tx); } static inline int is_netpoll_tx_blocked(struct net_device *dev) { - if (unlikely(netpoll_tx_running(dev))) - return atomic_read(&netpoll_block_tx); + if (static_branch_unlikely(&netpoll_block_tx)) + return netpoll_tx_running(dev); return 0; } #else -- 2.53.0.414.gf7e9f6c205-goog