netdev - Re: Very slow remove interface from kernel

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Date: Tue, 9 May 2023 14:10:01 +0300
From: Martin Zaharinov <micron10@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Ido Schimmel <idosch@...sch.org>,
 netdev <netdev@...r.kernel.org>
Subject: Re: Very slow remove interface from kernel

Hi

in short, there is no way to make the kernel do it faster.

Before time with old kernel unregister device make more faster .

with latest kernel >6.x this make very slow .


is there any chance to try to make this more fast.


m.


> On 9 May 2023, at 13:32, Eric Dumazet <edumazet@...gle.com> wrote:
> 
> 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.