From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cong Wang <xiyou.wangcong@gmail.com>
Subject: Re: [PATCH][next-next][v2] netlink: avoid to allocate full skb when
 sending to many devices
Date: Fri, 21 Sep 2018 12:08:32 -0700
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Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>
To: "Li,Rongqing" <lirongqing@baidu.com>
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On Thu, Sep 20, 2018 at 1:58 AM Li RongQing <lirongqing@baidu.com> wrote:
>
> if skb->head is vmalloc address, when this skb is delivered, full
> allocation for this skb is required, if there are many devices,
> the full allocation will be called for every devices

So why do you in practice need many netlink tap devices?

tap devices are now isolated in each netns, so at max you need
one tap device per netns in practice.