netdev - Re: [PATCH] net: bridge: add max_fdb

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Message-ID: <c90c8666-114c-fd5e-5b3e-e45234959c1a@prgmr.com>
Date:   Wed, 15 Nov 2017 11:43:34 -0800
From:   Sarah Newman <srn@...mr.com>
To:     netdev@...r.kernel.org
Subject: Re: [PATCH] net: bridge: add max_fdb_count

On 11/15/2017 11:27 AM, Sarah Newman wrote:
> Current memory and CPU usage for managing bridge fdb entries is unbounded.
> Add a parameter max_fdb_count, controlled from sysfs, which places an upper
> limit on the number of entries. Defaults to 1024.
> 
> When max_fdb_count is met or exceeded, whether traffic is sent out a
> given port should depend on its flooding behavior.
> 
> This may instead be mitigated by filtering mac address entries in the
> PREROUTING chain of the ebtables nat table, but this is only practical
> when mac addresses are known in advance.
> 
> Signed-off-by: Sarah Newman <srn@...mr.com>

I would love to improve this patch, but have limited time to devote to this...
What I would try first would be to maintain a data structure roughly ordered
based on both number of times an address was observed as well as age and evict
the least used, oldest entry when max_fdb_count was reached.

--Sarah