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From:   Yafang Shao <laoar.shao@gmail.com>
Date:   Sat, 28 Jul 2018 15:42:35 +0800
Message-ID: <CALOAHbAjtNf1LOhWEJMKNEEHSxjfEKiVV22KPUK88CTzt-eW0w@mail.gmail.com>
Subject: Re: [PATCH net-next 1/2] tcp: call tcp_drop() in tcp collapse
To:     Eric Dumazet <edumazet@google.com>
Cc:     David Miller <davem@davemloft.net>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Sat, Jul 28, 2018 at 11:38 AM, Eric Dumazet <edumazet@google.com> wrote:
> On Fri, Jul 27, 2018 at 8:35 PM Yafang Shao <laoar.shao@gmail.com> wrote:
>
>> So what about LINUX_MIB_TCPOFOMERGE ?
>> Regarding LINUX_MIB_TCPOFOMERGE,  a skb is already covered by another
>> skb, is that dropping the packet or simply lowering the memory
>> overhead ?
>
> What do you think ?
>
> If you receive two times the same payload, don't you have to drop one
> of the duplicate ?
>
> There is a a big difference between the two cases.

If the drop caused some data lost (which may then cause retransmition
or something), then this is a really DROP.
While if the drop won't cause any data lost, meaning it is a
non-harmful behavior, I think it should not be defined as DROP.
This is my suggestion anyway.

Thanks
Yafang