[ovs-discuss] ovn cpu high load problem

Han Zhou hzhou at ovn.org
Fri Dec 4 08:31:21 UTC 2020


On Thu, Dec 3, 2020 at 11:47 AM jre l <pdo2014 at hotmail.com> wrote:
>
> Dear everyone:
>
> Please help me。
>
> My ovn network running into trouble,this is a 250 client openstack+ovn
network,every time I make any change on network ,such as creating a
instance,the ovs-dbserver cpu went to 100%,and traffic grows to 1Gb/s, did
I meet a BUG?
>
>
>
> Here is client INFO:
>
> [root at client deploy]# rpm -qa|grep ovn
>
> openstack-neutron-ovn-metadata-agent-17.0.0-1.el8.noarch
>
> ovn2.13-20.09.0-2.el8.x86_64
>
> ovn2.13-host-20.09.0-2.el8.x86_64
>
>
>
> on client and server side CONFIG:
>
> ovs-vsctl set open . external-ids:ovn-encap-ip=10.0.1.10
>
> ovs-vsctl set open . external-ids:ovn-remote=tcp:10.0.1.103:6642,tcp:
10.0.1.104:6642,tcp:10.0.1.105:6642
>
> ovs-vsctl set open . external-ids:ovn-encap-type=geneve
>
> ovs-vsctl set open . external-ids:ovn-remote-probe-interval="60000"
>
> ovs-vsctl set open . external-ids:ovn-cms-options=enable-chassis-as-gw
>
>
>
> nb show error:
>
> [root@ controller tools]# netstat -pln|grep 6641
>
> tcp        0      0 172.16.16.103:6641      0.0.0.0:*
LISTEN      1112883/ovsdb-serve
>
>
>
> [root at controller tools]# ovn-nbctl --db=tcp:172.16.16.103:6641 show
>
> ovn-nbctl: tcp:172.16.16.103:6641: database connection failed ()
>
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It shouldn't trigger that much traffic for just one VM creation. Are you
sure the 1G traffic is triggered during just one VM creation?
Usually if you are bootstrapping the whole environment, i.e. when all HVs
starts to connect to SB at the same time, you would see SB overloaded.
After the system calms down, it shouldn't generate that much load.

How many logical routers and logical switches do you have? If there is a
big number of LR/LS and they all connected together (e.g. through an
external provider logical switch), it is possible to trigger a big payload
for monitor condition change when a VM is created, but it won't be 1G.
However, in such scenario it is possible to create unnecessary load to SB
DB, and setting the external-ids:ovn-monitor-all=true in all the HVs may
help.

Thanks,
Han
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