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bonding: convert unbalanced_load to per-cpu state

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A later patch widens the bonding TLB tx counters from u32 to u64. The
unbalanced_load counter sits in the transmit hot path, and cross-CPU
synchronization of a u64 would introduce measurable overhead. Convert
unbalanced_load to a per-cpu counter first so that the subsequent
widening only touches per-cpu data local to each CPU.

Introduce struct unbalanced_load_stats to hold the per-cpu counter,
and move the aggregation into a helper, reset_unbalanced_load(), which
sums all per-cpu instances. Use the delta of current total load vs
variable prev_total_unbalanced to calculate the loading.

Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Hangbin Liu <liuhangbin@kylinos.cn>
Acked-by: Jay Vosburgh <jv@jvosburgh.net>
Link: https://patch.msgid.link/20260831-bond_overflow-v6-1-ffb0ed1f7268@kylinos.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Hangbin Liu 2026-08-31 09:50:59 +08:00 committed by Jakub Kicinski
parent d0ec95a8a4
commit e147615635
2 changed files with 36 additions and 8 deletions
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37
drivers/net/bonding/bond_alb.c
View File

@ -133,6 +133,10 @@ static int tlb_initialize(struct bonding *bond)
if (!new_hashtbl)
return -ENOMEM;
bond_info->unbalanced_load = alloc_percpu(struct unbalanced_load_stats);
if (!bond_info->unbalanced_load)
goto out;
spin_lock_bh(&bond->mode_lock);
bond_info->tx_hashtbl = new_hashtbl;
@ -143,6 +147,10 @@ static int tlb_initialize(struct bonding *bond)
spin_unlock_bh(&bond->mode_lock);
return 0;
out:
kfree(new_hashtbl);
return -ENOMEM;
}
/* Must be called only after all slaves have been released */
@ -154,6 +162,8 @@ static void tlb_deinitialize(struct bonding *bond)
kfree(bond_info->tx_hashtbl);
bond_info->tx_hashtbl = NULL;
free_percpu(bond_info->unbalanced_load);
bond_info->prev_total_unbalanced = 0;
spin_unlock_bh(&bond->mode_lock);
}
@ -1345,7 +1355,7 @@ static netdev_tx_t bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond,
/* unbalanced or unassigned, send through primary */
tx_slave = rcu_dereference(bond->curr_active_slave);
if (bond->params.tlb_dynamic_lb)
bond_info->unbalanced_load += skb->len;
this_cpu_add(bond_info->unbalanced_load->tx_bytes, skb->len);
}
if (tx_slave && bond_slave_can_tx(tx_slave)) {
@ -1529,6 +1539,23 @@ netdev_tx_t bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
return bond_do_alb_xmit(skb, bond, tx_slave);
}
static u32 reset_unbalanced_load(struct alb_bond_info *bond_info)
{
struct unbalanced_load_stats *p;
u32 delta, total_bytes = 0;
int i;
for_each_possible_cpu(i) {
p = per_cpu_ptr(bond_info->unbalanced_load, i);
total_bytes += READ_ONCE(p->tx_bytes);
}
delta = total_bytes - bond_info->prev_total_unbalanced;
bond_info->prev_total_unbalanced = total_bytes;
return delta / BOND_TLB_REBALANCE_INTERVAL;
}
void bond_alb_monitor(struct work_struct *work)
{
struct bonding *bond = container_of(work, struct bonding,
@ -1570,12 +1597,8 @@ void bond_alb_monitor(struct work_struct *work)
if (atomic_read(&bond_info->tx_rebalance_counter) >= BOND_TLB_REBALANCE_TICKS) {
bond_for_each_slave_rcu(bond, slave, iter) {
tlb_clear_slave(bond, slave, 1);
if (slave == rcu_access_pointer(bond->curr_active_slave)) {
SLAVE_TLB_INFO(slave).load =
bond_info->unbalanced_load /
BOND_TLB_REBALANCE_INTERVAL;
bond_info->unbalanced_load = 0;
}
if (slave == rcu_access_pointer(bond->curr_active_slave))
SLAVE_TLB_INFO(slave).load = reset_unbalanced_load(bond_info);
}
atomic_set(&bond_info->tx_rebalance_counter, 0);
}

7
include/net/bond_alb.h
View File

@ -123,9 +123,14 @@ struct tlb_slave_info {
*/
};
struct unbalanced_load_stats {
u32 tx_bytes;
};
struct alb_bond_info {
struct tlb_client_info *tx_hashtbl; /* Dynamically allocated */
u32 unbalanced_load;
struct unbalanced_load_stats __percpu *unbalanced_load;
u32 prev_total_unbalanced;
atomic_t tx_rebalance_counter;
int lp_counter;
/* -------- rlb parameters -------- */