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

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Date:   Thu, 16 Nov 2017 15:13:35 +0900
From:   Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:     Sarah Newman <srn@...mr.com>, Andrew Lunn <andrew@...n.ch>,
        Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH] net: bridge: add max_fdb_count

On 2017/11/16 13:54, Sarah Newman wrote:
> On 11/15/2017 08:05 PM, Toshiaki Makita wrote:
>> On 2017/11/16 11:25, Andrew Lunn wrote:
>>>> Also what do the vendors using bridge for L2 offload to switch think?
>>>
>>> The Marvell L2 switches which DSA supports have 8K FDB/MDB entries. So
>>> maybe 1024 is a bit low?
>>
>> How about U32_MAX by default since it is currently not restricted.
>> (assuming the field will be changed to u32 as per Stephen's feedback).
>>
>> Otherwise users may suffer from unexpected behavior change by updating
>> kernel?
>>
> 
> U32_MAX seems like much too high a default to be helpful to a typical user. How many devices are realistically on a single bridge in the wild? Double
> that seems like a reasonable default.

I'm suggesting the most unrealistic number to essentially disable the
restriction by default.
My understanding is that we put a priority on not to break existing
users even if the new restriction looks reasonable for most people.

-- 
Toshiaki Makita