netdev - Re: Very slow remove interface from kernel

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Date: Tue, 9 May 2023 12:32:40 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Ido Schimmel <idosch@...sch.org>
Cc: Martin Zaharinov <micron10@...il.com>, netdev <netdev@...r.kernel.org>
Subject: Re: Very slow remove interface from kernel

On Tue, May 9, 2023 at 12:20 PM Ido Schimmel <idosch@...sch.org> wrote:
>
> On Tue, May 09, 2023 at 11:22:13AM +0300, Martin Zaharinov wrote:
> > add vlans :
> > for i in $(seq 2 4094); do ip link add link eth1 name vlan$i type vlan id $i; done
> > for i in $(seq 2 4094); do ip link set dev vlan$i up; done
> >
> >
> > and after that run :
> >
> > for i in $(seq 2 4094); do ip link del link eth1 name vlan$i type vlan id $i; done
> >
> >
> > time for remove for this 4093 vlans is 5-10 min .
> >
> > Is there options to make fast this ?
>
> If you know you are going to delete all of them together, then you can
> add them to the same group during creation:
>
> for i in $(seq 2 4094); do ip link add link eth1 name vlan$i up group 10 type vlan id $i; done
>
> Then delete the group:
>
> ip link del group 10
>

Another way is to create a netns for retiring devices,
move devices to the 'retirens' when they need to go away.

Then once per minute, delete the retirens and create a new one.

-> This batches netdev deletions.


> IIRC, in the past there was a patchset to allow passing a list of
> ifindexes instead of a group number, but it never made its way upstream.