MIRRORS/linux-yocto
1
0
Fork 0
mirror of git://git.yoctoproject.org/linux-yocto.git synced 2026-01-27 12:47:24 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

net: use llist for sd->defer_list

Browse Source 
Get rid of sd->defer_lock and adopt llist operations.

We optimize skb_attempt_defer_free() for the common case,
where the packet is queued. Otherwise sd->defer_count
is increasing, until skb_defer_free_flush() clears it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250928084934.3266948-3-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Eric Dumazet 2025-09-28 08:49:33 +00:00 committed by Paolo Abeni
parent 9c94ae6bb0
commit 844c9db7f7
3 changed files with 17 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/linux/netdevice.h
View File

@ -3537,10 +3537,10 @@ struct softnet_data {
struct numa_drop_counters drop_counters;
/* Another possibly contended cache line */
spinlock_t defer_lock ____cacheline_aligned_in_smp;
atomic_t defer_count;
int defer_ipi_scheduled;
struct sk_buff *defer_list;
struct llist_head defer_list ____cacheline_aligned_in_smp;
atomic_long_t defer_count;
int defer_ipi_scheduled ____cacheline_aligned_in_smp;
call_single_data_t defer_csd;
};

18
net/core/dev.c
View File

@ -6717,22 +6717,16 @@ EXPORT_SYMBOL(napi_complete_done);
static void skb_defer_free_flush(struct softnet_data *sd)
{
struct llist_node *free_list;
struct sk_buff *skb, *next;
/* Paired with WRITE_ONCE() in skb_attempt_defer_free() */
if (!READ_ONCE(sd->defer_list))
if (llist_empty(&sd->defer_list))
return;
atomic_long_set(&sd->defer_count, 0);
free_list = llist_del_all(&sd->defer_list);
spin_lock(&sd->defer_lock);
skb = sd->defer_list;
sd->defer_list = NULL;
atomic_set(&sd->defer_count, 0);
spin_unlock(&sd->defer_lock);
while (skb != NULL) {
next = skb->next;
llist_for_each_entry_safe(skb, next, free_list, ll_node) {
napi_consume_skb(skb, 1);
skb = next;
}
}
@ -12995,7 +12989,7 @@ static int __init net_dev_init(void)
sd->cpu = i;
#endif
INIT_CSD(&sd->defer_csd, trigger_rx_softirq, sd);
spin_lock_init(&sd->defer_lock);
init_llist_head(&sd->defer_list);
gro_init(&sd->backlog.gro);
sd->backlog.poll = process_backlog;

15
net/core/skbuff.c
View File

@ -7185,6 +7185,7 @@ static void kfree_skb_napi_cache(struct sk_buff *skb)
*/
void skb_attempt_defer_free(struct sk_buff *skb)
{
unsigned long defer_count;
int cpu = skb->alloc_cpu;
struct softnet_data *sd;
unsigned int defer_max;
@ -7202,17 +7203,15 @@ nodefer: kfree_skb_napi_cache(skb);
sd = &per_cpu(softnet_data, cpu);
defer_max = READ_ONCE(net_hotdata.sysctl_skb_defer_max);
if (atomic_read(&sd->defer_count) >= defer_max)
defer_count = atomic_long_inc_return(&sd->defer_count);
if (defer_count >= defer_max)
goto nodefer;
spin_lock_bh(&sd->defer_lock);
/* Send an IPI every time queue reaches half capacity. */
kick = (atomic_inc_return(&sd->defer_count) - 1) == (defer_max >> 1);
llist_add(&skb->ll_node, &sd->defer_list);
skb->next = sd->defer_list;
/* Paired with READ_ONCE() in skb_defer_free_flush() */
WRITE_ONCE(sd->defer_list, skb);
spin_unlock_bh(&sd->defer_lock);
/* Send an IPI every time queue reaches half capacity. */
kick = (defer_count - 1) == (defer_max >> 1);
/* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
* if we are unlucky enough (this seems very unlikely).