From: Nikolay Aleksandrov <niko...@cumulusnetworks.com> Date: Sat, 11 Jun 2016 18:17:53 +0200
> Oops, I almost missed the v2, sorry about that. So, technically it > looks correct, but I only fear the scalability impact of the > change. If there're a large number of vlans adding a macvlan (or any > device that syncs uc addr) might become very slow and every flag > change will become very slow too without an option to revert to the > original behaviour so we'll have to wait for the entries to be added > in order to delete them. Another common scenario is having 8021q > interfaces on top of the bridge with different mac addresses for > some of the configured vlans (or with macvlans on top of them for > VRR), that use case would suffer as well because their macs need to > be local only for those vlans, and not the 2000+ other vlans that > might exist. On every sync_uc() call all the fdb entries get > deleted and added again, so even after deleting some manually they > can come back unexpectedly after some operation and also the message > storm from all the deletes and adds could be problematic as well. > > > E.g. 2000 br0 vlans, 25 macvlans on br0 (adding them took more than 5 > minutes, 53k fdb entries): > $ bridge fdb del de:8e:9f:16:c5:71 dev br0 vlan 289 > $ ip l set br0 multicast on > $ bridge fdb | grep 289 | grep de:8e:9f:16:c5:71 > de:8e:9f:16:c5:71 dev br0 vlan 1289 master br0 permanent > de:8e:9f:16:c5:71 dev br0 vlan 289 master br0 permanent > > In fact you can't escape the slow performance even if you delete all > entries because on the next flag change or interface add, they will > be added back. Yeah, I think the performance implications are too severe too, I'm not applying this.
