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Subject: Re: [PATCH net-next] net: init sk_cookie for inet socket
To:     David Miller <davem@davemloft.net>, laoar.shao@gmail.com
Cc:     eric.dumazet@gmail.com, alexei.starovoitov@gmail.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
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 <20180423.115821.640630949143585629.davem@davemloft.net>
From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <788ce3f1-6534-5c2e-1870-5ebd8ea4ae7f@gmail.com>
Date:   Mon, 23 Apr 2018 09:09:34 -0700
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On 04/23/2018 08:58 AM, David Miller wrote:
> From: Yafang Shao <laoar.shao@gmail.com>
> Date: Sun, 22 Apr 2018 21:50:04 +0800
> 
>> With sk_cookie we can identify a socket, that is very helpful for
>> traceing and statistic, i.e. tcp tracepiont and ebpf.
>> So we'd better init it by default for inet socket.
>> When using it, we just need call atomic64_read(&sk->sk_cookie).
>>
>> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> 
> Applied, thank you.
> 

This is adding yet another atomic_inc on a global cache line.

Most applications do not need the cookie being ever set.

The existing mechanism was fine. Set it on demand.