netdev - Re: RFC: Should net namespaces scale up (>10k) ?

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Message-ID: <e74ac4d7-44df-43f0-8b5d-46ef6697604f@orange.com>
Date: Tue, 17 Sep 2024 00:05:59 +0200
From: Alexandre Ferrieux <alexandre.ferrieux@...il.com>
To: Simon Horman <horms@...nel.org>,
 Przemek Kitszel <przemyslaw.kitszel@...el.com>
Cc: Alexandre Ferrieux <alexandre.ferrieux@...il.com>,
 Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org
Subject: Re: RFC: Should net namespaces scale up (>10k) ?

On 16/09/2024 16:01, Simon Horman wrote:
> 
>> > Any insight on the (possibly very good) reasons those two apparent
>> > warts stand in the way of netns scaling up ?
>> 
>> I guess that the reason is more pragmatic, net namespaces are decade
>> older than xarray, thus list-based implementation.
> 
> Yes, I would also guess that the reason is not that these limitations were
> part of the design. But just that the implementation scaled sufficiently at
> the time. And that if further scale is required, then the implementation
> can be updated.

Okay, thank you for confirming my fears :}
Now, what shall we do:

 1. Ignore this corner case and carve the "few netns" assumption in stone;

 2. Migrate netns IDs to xarrays (not to mention other leftover uses of IDR).

Note that this funny workload of mine is a typical situation where the "DPDK
beats Linux" myth gets reinforced. I find this pretty disappointing, as it
implies reinventing the whole network stack in userspace. All the more so, as
the other typical case for DPDK is now moot thanks to XDP.

What do you think ?