diff options
Diffstat (limited to 'net/core/skbuff.c')
| -rw-r--r-- | net/core/skbuff.c | 51 |
1 files changed, 50 insertions, 1 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 30b523fa4ad2..028a280fbabd 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -204,7 +204,7 @@ static void __build_skb_around(struct sk_buff *skb, void *data, skb_set_end_offset(skb, size); skb->mac_header = (typeof(skb->mac_header))~0U; skb->transport_header = (typeof(skb->transport_header))~0U; - + skb->alloc_cpu = raw_smp_processor_id(); /* make sure we initialize shinfo sequentially */ shinfo = skb_shinfo(skb); memset(shinfo, 0, offsetof(struct skb_shared_info, dataref)); @@ -1037,6 +1037,7 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old) #ifdef CONFIG_NET_RX_BUSY_POLL CHECK_SKB_FIELD(napi_id); #endif + CHECK_SKB_FIELD(alloc_cpu); #ifdef CONFIG_XPS CHECK_SKB_FIELD(sender_cpu); #endif @@ -6486,3 +6487,51 @@ free_now: } EXPORT_SYMBOL(__skb_ext_put); #endif /* CONFIG_SKB_EXTENSIONS */ + +/** + * skb_attempt_defer_free - queue skb for remote freeing + * @skb: buffer + * + * Put @skb in a per-cpu list, using the cpu which + * allocated the skb/pages to reduce false sharing + * and memory zone spinlock contention. + */ +void skb_attempt_defer_free(struct sk_buff *skb) +{ + int cpu = skb->alloc_cpu; + struct softnet_data *sd; + unsigned long flags; + bool kick; + + if (WARN_ON_ONCE(cpu >= nr_cpu_ids) || + !cpu_online(cpu) || + cpu == raw_smp_processor_id()) { + __kfree_skb(skb); + return; + } + + sd = &per_cpu(softnet_data, cpu); + /* We do not send an IPI or any signal. + * Remote cpu will eventually call skb_defer_free_flush() + */ + spin_lock_irqsave(&sd->defer_lock, flags); + skb->next = sd->defer_list; + /* Paired with READ_ONCE() in skb_defer_free_flush() */ + WRITE_ONCE(sd->defer_list, skb); + sd->defer_count++; + + /* kick every time queue length reaches 128. + * This should avoid blocking in smp_call_function_single_async(). + * This condition should hardly be bit under normal conditions, + * unless cpu suddenly stopped to receive NIC interrupts. + */ + kick = sd->defer_count == 128; + + spin_unlock_irqrestore(&sd->defer_lock, flags); + + /* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU + * if we are unlucky enough (this seems very unlikely). + */ + if (unlikely(kick)) + smp_call_function_single_async(cpu, &sd->defer_csd); +} |