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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
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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>

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

:)