[PATCH v1 net-next] bonding: Optimise is_netpoll_tx_blocked().
flat view
STALE230d
LANDED
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-02-23 23:07:52
Subsystem:
bonding driver, networking drivers, networking [general], the rest · Maintainers:
Jay Vosburgh, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Landed in mainline as fc1f97929ada on 2026-02-25.
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 <redacted>
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
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