netdev - Re: [PATCH net-next] net: do not create fallback tunnels for non-default namespaces

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Message-Id: <20180309.112350.1061969650325938370.davem@davemloft.net>
Date:   Fri, 09 Mar 2018 11:23:50 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next] net: do not create fallback tunnels for
 non-default namespaces

From: Eric Dumazet <edumazet@...gle.com>
Date: Thu,  8 Mar 2018 12:51:41 -0800

> fallback tunnels (like tunl0, gre0, gretap0, erspan0, sit0,
> ip6tnl0, ip6gre0) are automatically created when the corresponding
> module is loaded.
> 
> These tunnels are also automatically created when a new network
> namespace is created, at a great cost.
> 
> In many cases, netns are used for isolation purposes, and these
> extra network devices are a waste of resources. We are using
> thousands of netns per host, and hit the netns creation/delete
> bottleneck a lot. (Many thanks to Kirill for recent work on this)
> 
> Add a new sysctl so that we can opt-out from this automatic creation.
> 
> Note that these tunnels are still created for the initial namespace,
> to be the least intrusive for typical setups.
> 
> Tested:
 ...
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied, thanks Eric.