netdev - Re: [PATCH] net: increase skb->users instead of skb

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Message-ID: <AANLkTi=Ri40-q20tvrRwMDcrUVVHQ69FFtGrM4NRbuuE@mail.gmail.com>
Date:	Fri, 17 Dec 2010 08:24:49 +0800
From:	Junchang Wang <junchangwang@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Changli Gao <xiaosuo@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Tom Herbert <therbert@...gle.com>,
	Jiri Pirko <jpirko@...hat.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Xinan Tang <xinan.tang@...el.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] net: increase skb->users instead of skb_clone()

On Thu, Dec 16, 2010 at 10:41 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> But, if we have N receivers, we get only the last one win - the first N-1 will
>> call deliver_skb().
>>
>
> Yes, but you want to, because each receiver has to make a private copy
> of the skb.
>
> The big win is that if packet if filtered out (not accepted by the
> socket filter), you end with no extra skb_clone() at all.
>
> Say you have 8 receivers, with a filter matching some hash/cpu, and only
> one af_packet socket will take the message.
>
> Before patch : 8 skb_clones()
>
> After patch : one skb_clone()
>
Now I understand. :)
The patch is fine. Thanks Changli and Eric.



-- 
--Junchang
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