[ovs-dev] [PATCH] mac-learning: Increase default mac table size to 8K from 2K

[Eelco Chaudron]

On 27 Jun 2018, at 17:11, Ben Pfaff wrote:

> On Wed, Jun 27, 2018 at 05:02:31PM +0200, Eelco Chaudron wrote:
>>
>>
>> On 27 Jun 2018, at 16:09, Ben Pfaff wrote:
>>
>>> On Wed, Jun 27, 2018 at 01:24:25PM +0200, Eelco Chaudron wrote:
>>>> In field deployments of OVS (mostly in combination with OpenStack) 
>>>> we
>>>> see that the 2K default MAC forwarding table is too small.
>>>>
>>>> On average this tables is around 5k entries, hence this patch to
>>>> increase the default value to the next power of 2, i.e. 8K.
>>>>
>>>> This increase in size does not automatically increase the memory
>>>> footprint, as the memory for the MAC entries, are allocated only 
>>>> when
>>>> needed.
>>>>
>>>> Signed-off-by: Eelco Chaudron <echaudro at redhat.com>
>>>
>>> Applied, thanks!
>>
>> Ben thanks for applying so quickly, however, I seem to have messed up 
>> the
>> number :(
>>
>> 5K, was 50K (I counted zero’s wrong), which leads to 64K entries by 
>> default.
>>
>> This might make other people more opposed to the change, as it could 
>> result
>> in a lot of memory being eaten when someone does a MAC sweep 
>> (attack),
>> around 4Mbyte per bridge.
>>
>> Any input here?
>
> 64k does seem like a lot.
>
> Maybe OpenStack deployments should just set the configuration value in
> the database to whatever they really need?

Yes now seeing the 50K requirement it would be better to do it at the 
OSP level. Sorry for the work, I guess you can rollback the patch.

Thanks,

Eelco