2017-07-17 15:32 GMT+08:00 Eric Dumazet <eric.duma...@gmail.com>:
> On Mon, 2017-07-17 at 10:22 +0800, Lin Zhang wrote:
>> In the pull_pages code block, if the first frag size > eat,
>> we can end the loop in advance to avoid extra copy.
>>
>> Signed-off-by: Lin Zhang <xiaolou4...@gmail.com>
>> ---
>> net/core/skbuff.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
>> index f990eb8..c00a1df 100644
>> --- a/net/core/skbuff.c
>> +++ b/net/core/skbuff.c
>> @@ -1720,6 +1720,10 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta)
>> skb_shinfo(skb)->frags[k].page_offset += eat;
>> skb_frag_size_sub(&skb_shinfo(skb)->frags[k],
>> eat);
>> eat = 0;
>> + if (!i) {
>> + k = skb_shinfo(skb)->nr_frags;
>> + break;
>> + }
>> }
>> k++;
>> }
>
> -CC lkml (no need to spam lkml for netdev patches )
>
> Why even reading skb_shinfo(skb)->nr_frags to write it again ?
>
> I would use something like :
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index
> 8b11341ed69ad97d34dd3e9b73c8c44ef7c452ff..a562b0e61afa3faf7abdd7f9209ae9096310fb7d
> 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1719,13 +1719,15 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta)
> if (eat) {
> skb_shinfo(skb)->frags[k].page_offset += eat;
> skb_frag_size_sub(&skb_shinfo(skb)->frags[k],
> eat);
> + if (!i)
> + goto end;
> eat = 0;
> }
> k++;
> }
> }
> skb_shinfo(skb)->nr_frags = k;
> -
> +end:
> skb->tail += delta;
> skb->data_len -= delta;
>
>
>
>
>
Yes, this change it is looks like better than me. :)
--
Lin Zhang
