提交 0a463c78 编写于 作者: P Paolo Abeni 提交者: David S. Miller

udp: avoid a cache miss on dequeue

Since UDP no more uses sk->destructor, we can clear completely
the skb head state before enqueuing. Amend and use
skb_release_head_state() for that.

All head states share a single cacheline, which is not
normally used/accesses on dequeue. We can avoid entirely accessing
such cacheline implementing and using in the UDP code a specialized
skb free helper which ignores the skb head state.

This saves a cacheline miss at skb deallocation time.

v1 -> v2:
  replaced secpath_reset() with skb_release_head_state()
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
上级 3889a803
......@@ -880,10 +880,12 @@ static inline bool skb_unref(struct sk_buff *skb)
return true;
}
void skb_release_head_state(struct sk_buff *skb);
void kfree_skb(struct sk_buff *skb);
void kfree_skb_list(struct sk_buff *segs);
void skb_tx_error(struct sk_buff *skb);
void consume_skb(struct sk_buff *skb);
void consume_stateless_skb(struct sk_buff *skb);
void __kfree_skb(struct sk_buff *skb);
extern struct kmem_cache *skbuff_head_cache;
......
......@@ -643,12 +643,10 @@ static void kfree_skbmem(struct sk_buff *skb)
kmem_cache_free(skbuff_fclone_cache, fclones);
}
static void skb_release_head_state(struct sk_buff *skb)
void skb_release_head_state(struct sk_buff *skb)
{
skb_dst_drop(skb);
#ifdef CONFIG_XFRM
secpath_put(skb->sp);
#endif
secpath_reset(skb);
if (skb->destructor) {
WARN_ON(in_irq());
skb->destructor(skb);
......@@ -751,6 +749,24 @@ void consume_skb(struct sk_buff *skb)
}
EXPORT_SYMBOL(consume_skb);
/**
* consume_stateless_skb - free an skbuff, assuming it is stateless
* @skb: buffer to free
*
* Works like consume_skb(), but this variant assumes that all the head
* states have been already dropped.
*/
void consume_stateless_skb(struct sk_buff *skb)
{
if (!skb_unref(skb))
return;
trace_consume_skb(skb);
if (likely(skb->head))
skb_release_data(skb);
kfree_skbmem(skb);
}
void __kfree_skb_flush(void)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
......
......@@ -1359,7 +1359,8 @@ void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
sk_peek_offset_bwd(sk, len);
unlock_sock_fast(sk, slow);
}
consume_skb(skb);
consume_stateless_skb(skb);
}
EXPORT_SYMBOL_GPL(skb_consume_udp);
......@@ -1739,6 +1740,9 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
sk_mark_napi_id_once(sk, skb);
}
/* clear all pending head states while they are hot in the cache */
skb_release_head_state(skb);
rc = __udp_enqueue_schedule_skb(sk, skb);
if (rc < 0) {
int is_udplite = IS_UDPLITE(sk);
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册