[openstack-dev] [neutron] performance issue between virtual networks

Brian Haley haleyb.dev at gmail.com
Tue Jan 2 16:02:08 UTC 2018



On 12/27/2017 08:39 AM, Kim-Norman Sahm wrote:
> Hi,
> 
> i've detected a performance issue by accessing an floating ip in a
> different openstack network (same tenant).
> 
> example:
> i have one tenant with two internal networks.
> each network has its own vrouter which is connectet to the extnet.
> the physical network infrastructure is 10Gbit/s.
> 
>           networkA
>     VM1 ------|               extnet
>               |----|vrouter1|----|
>     VM2 ------|                  |
>                                  |---ext
>           networkB               |
>     VM3 ------|                  |
>               |----|vrouter2|----|
>     VM4 ------|
> 
> VM1 -> VM2	~8,6Gbit/s
> VM3 -> VM4	~8,6GBit/s
> VM1 -> vrouter1	~8.6GBit/s
> VM4 -> vrouter2 ~8,6GBit/s
> vrouter1 -> vrouter2 ~8,6Gbits
> VM1 -> VM4	~2,5GBit/s
> VM1 -> vrouter2 ~2,5Gbit/s

I could only guess that vrouter1 and vrouter2 are on different nodes, so 
you're losing some performance going from virtual to physical and back 
(eg GSO).  Have you tried this for reference:

VM1 -> system on extnet
VM4 -> system on extnet

Also, are you sure when packets from VM1 -> VM4 leave the vrouter1 
interface they are still at the higher MTU?

-Brian


> 
> detected with iperf3
> it's an openstack newton environment with openvswitch 2.6.1
> VXLAN mtu is 8950 and 9000 for physical interfaces
> 
> does anybody has an idea what could be the cause of the performance
> issue?
> 
> Best regards
> Kim
> 
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