On Fri, May 16, 2014 at 09:38:27PM +0400, Andrey Korolyov wrote:
> Can anyone please explain following performance impact:
>
> Taking following snippet of forward table (one-way traffic cleaner), I
> am observing very huge CPU impact on the ovs-vswitchd on the specific
> test for IP address violation, but it seemingly comes from nowhere -
> packets should be silently dropped by kernel module since there is a
> definitely 'drop' action for unicast IP flood from following:
>
> hping3 -1 --flood --rand-source 10.0.0.51 <-- active neighbour
>
> As one can see from counters, packets are dropping, but raising CPU
> consumption of the ovs-vswitchd up to four cores on E5 cpu, instead of
> being silently blackholed by kernel module. When no path to neighbor
> with certain address exists (for example, if one shut down interface
> 10.0.0.51), overhead disappears. Can anyone have a point on what can be
> fixed there to not heat up vswitchd process so much? I am using 2.1
> series userspace tools.
I think you need to turn on prefix tracking to get the best
performance out of this flow table. Try this:
ovs-vsctl \
-- set Bridge br0 flow_tables:2=@N2 \
-- --id=@N2 create Flow_Table name=table2 prefixes=ip_dst,ip_src
You'll need to replace br0 by the name of your bridge.
We've had discussion of enabling prefix tracking by default. I
thought that we had concluded that it was a good idea, but it doesn't
seem to be on master yet. I'll follow up on that.
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