[ovs-discuss] High CPU load (up to 100%) with OVS+DPDK+vHOST usage.

[Loftus, Ciara]

> 
> Hello.
> I am trying to build VM to VM scheme using Open vSwitch 2.3.9 and DPDK
> 2.0.0.
> After building and installing OVS+DPDK I'm running single bridge with extra
> port dpdkvhost type.
> I'm using user-defined vhost device called vhost-net1.
> 
> 
> #ovs-vswitchd --dpdk --cuse_dev_name vhost-net1 -c 0x01 -n 4 --socket-
> mem 1024,0 -- unix:/usr/local/var/run/openvswitch/db.sock --pidfile --
> detach
> 
> 014d4a3f-0a8a-4d8f-8fc3-222775266ebf
>     Bridge "br10"
>         Port "dpdkvhost0"
>             Interface "dpdkvhost0"
>                 type: dpdkvhost
>         Port "br10"
>             Interface "br10"
>                 type: internal
> 
> Then I'm trying to run single KVM VM using qemu 2.0 (pretty old with -mem-
> prealloc option)

This will not work. If you are using the mem-prealloc & associated arguments you mention below,
you will need to use QEMU v1.6.2. If you wish to use a newer version of QEMU than v1.6.2, you will
need to use at least v2.1.0, with the -object memory-backend-file arguments, as documented in
INSTALL.DPDK.md.

> 
> #/usr/bin/qemu-system-x86_64
>  -name qemu_smatov-0 -cpu host -m 2048 -smp 2 -boot once=c -drive
> file=/var/lib/libvirt/images/qemu_smatov-0.qcow2 -enable-kvm -net none -
> mem-path /mnt/huge -numa node,memdev=mem -mem-prealloc -netdev
> type=tap,id=net1,script=no,downscript=no,ifname=dpdkvhost0,vhost=on,v
> hostfd=3 -device virtio-net-
> pci,netdev=net1,mac=52:54:f1:61:4c:84,csum=off,gso=off,guest_tso4=off,gu
> est_tso6=off,guest_ecn=off
> 

[...]

> 
> Does this usage of CPU expected?
> 
> And, btw, does I need any extra guest VM configuration to run ping/iperf?
> --
> 
> Sergey Matov