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| author | Eric Dumazet <edumazet@google.com> | 2014-09-22 16:29:32 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-26 15:40:06 -0400 |
| commit | f4a775d14489a801a5b8b0540e23ab82e2703091 (patch) | |
| tree | fea57ec3004b0586f0fc25f4cf3f0dc8631dcb5f /include/linux/skbuff.h | |
| parent | aebac744932439b5f869869f07f406a9cced465d (diff) | |
| download | talos-obmc-linux-f4a775d14489a801a5b8b0540e23ab82e2703091.tar.gz talos-obmc-linux-f4a775d14489a801a5b8b0540e23ab82e2703091.zip | |
net: introduce __skb_header_release()
While profiling TCP stack, I noticed one useless atomic operation
in tcp_sendmsg(), caused by skb_header_release().
It turns out all current skb_header_release() users have a fresh skb,
that no other user can see, so we can avoid one atomic operation.
Introduce __skb_header_release() to clearly document this.
This gave me a 1.5 % improvement on TCP_RR workload.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/skbuff.h')
| -rw-r--r-- | include/linux/skbuff.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index f1bfa3781c75..8eaa62400fca 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1083,6 +1083,7 @@ static inline int skb_header_cloned(const struct sk_buff *skb) * Drop a reference to the header part of the buffer. This is done * by acquiring a payload reference. You must not read from the header * part of skb->data after this. + * Note : Check if you can use __skb_header_release() instead. */ static inline void skb_header_release(struct sk_buff *skb) { @@ -1092,6 +1093,20 @@ static inline void skb_header_release(struct sk_buff *skb) } /** + * __skb_header_release - release reference to header + * @skb: buffer to operate on + * + * Variant of skb_header_release() assuming skb is private to caller. + * We can avoid one atomic operation. + */ +static inline void __skb_header_release(struct sk_buff *skb) +{ + skb->nohdr = 1; + atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT)); +} + + +/** * skb_shared - is the buffer shared * @skb: buffer to check * |
