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

Ben Pfaff blp at ovn.org
Wed Jun 27 15:11:18 UTC 2018

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?

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