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From:   Cong Wang <xiyou.wangcong@gmail.com>
Date:   Thu, 19 Jul 2018 10:12:23 -0700
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Subject: Re: [PATCH RFC/RFT net-next 00/17] net: Convert neighbor tables to per-namespace
To:     David Ahern <dsahern@gmail.com>
Cc:     David Miller <davem@davemloft.net>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        nikita.leshchenko@oracle.com,
        Roopa Prabhu <roopa@cumulusnetworks.com>,
        Stephen Hemminger <stephen@networkplumber.org>,
        Ido Schimmel <idosch@mellanox.com>,
        Jiri Pirko <jiri@mellanox.com>,
        Saeed Mahameed <saeedm@mellanox.com>,
        Alexander Aring <alex.aring@gmail.com>,
        linux-wpan@vger.kernel.org,
        NetFilter <netfilter-devel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Jul 19, 2018 at 9:16 AM David Ahern <dsahern@gmail.com> wrote:
>
> Chatting with Nikolay about this and he brought up a good corollary - ip
> fragmentation. It really is a similar problem in that memory is consumed
> as a result of packets received from an external entity. The ipfrag
> sysctls are per namespace with a limit that non-init_net namespaces can
> not set high_thresh > the current value of init_net. Potential memory
> consumed by fragments scales with the number of namespaces which is the
> primary concern with making neighbor tables per namespace.

Nothing new, already discussed:
https://marc.info/?l=linux-netdev&m=140391416215988&w=2

:)