[ovs-discuss] Open vSwitch performance with UDP traffic

Ben Pfaff blp at nicira.com
Tue Jan 21 22:55:45 UTC 2014


On Tue, Jan 21, 2014 at 10:50:30PM +0000, McGarvey, Kevin wrote:
> I am sending UDP DNS queries to a KVM guest through Open vSwitch
> running on the RHEL hypervisor.  With traffic of only 5K
> request/response pairs per second the CPU consumption of the
> ovs-vswitchd process is over 60%. The source IP and port change with
> each request, simulating normal UDP DNS traffic.  It appears that
> each request is being handled as a new flow and is being sent to the
> userspace process.  When I dump data flows with ovs-dpctl, there are
> thousands of flows that are never used.
> 
> Is there a way to get reasonable performance from Open vSwitch with
> this type of traffic?  I tried adding a flow with ovs-ofctl,
> specifying the destination MAC of the guest and everything else
> wildcarded, but I saw no change in the CPU consumption of
> ovs-vswitchd.

You didn't say what version of OVS you're using.  The CPU% used for
this kind of traffic should drop dramatically with an upgrade to 1.11
or later.



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