[Openstack] Directional network performance issues with Neutron + OpenvSwitch

Rick Jones rick.jones2 at hp.com
Fri Oct 25 15:44:01 UTC 2013

On 10/25/2013 08:19 AM, Martinx - ジェームズ wrote:
> I think can say... "YAY!!"    :-D
> With "LibvirtOpenVswitchDriver" my internal communication is the double
> now! It goes from ~200 (with LibvirtHybridOVSBridgeDriver) to
> *_400Mbit/s_* (with LibvirtOpenVswitchDriver)! Still far from 1Gbit/s
> (my physical path limit) but, more acceptable now.
> The command "ethtool -K eth1 gro off" still makes no difference.

Does GRO happen if there isn't RX CKO on the NIC?  Can your NIC 
peer-into a GRE tunnel (?) to do CKO on the encapsulated traffic?

> So, there is only 1 remain problem, when traffic pass trough L3 /
> Namespace, it is still useless. Even the SSH connection into my
> Instances, via its Floating IPs, is slow as hell, sometimes it just
> stops responding for a few seconds, and becomes online again
> "out-of-nothing"...
> I just detect a weird "behavior", when I run "apt-get update" from
> instance-1, it is slow as I said plus, its ssh connection (where I'm
> running apt-get update), stops responding right after I run "apt-get
> update" AND, _all my others ssh connections also stops working too!_ For
> a few seconds... This means that when I run "apt-get update" from within
> instance-1, the SSH session of instance-2 is affected too!! There is
> something pretty bad going on at L3 / Namespace.
> BTW, do you think that a ~400MBit/sec intra-vm-communication (GRE
> tunnel) on top of a 1Gbit ethernet is acceptable?! It is still less than
> a half...

I would suggest checking for individual CPUs maxing-out during the 400 
Mbit/s transfers.

rick jones

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