[ovs-discuss] OVS 2.5.1 high CPU load when running full table BGP sessions

Petr Marciniak petr at datapath.io
Wed Nov 23 10:27:11 UTC 2016

Hi Ben,

On 22.11.2016 23:23, Ben Pfaff wrote:
> On Sun, Nov 20, 2016 at 01:47:41PM +0100, petr at datapath.io wrote:
>> We're running an OVS 2.5.1 switch on a server which also maintains
>> couple of BGP sessions (Quagga) for IP transit each receiving full table.
>> As soon as routes learned from Quagga propagate into the kernel routing
>> table OVS goes on 100% CPU. It seems that it is learning/caching all the
>> routes from kernel for itself.
>> Is there any way to disable this functionality? We solved this problem
>> by downgrading to 2.3.1, but do not want to downgrade kernel versions.
> We can't tell what OVS is actually doing without more information.
> What's showing up in the logs?

Unfortunately, I don't have the log messages at hand anymore.

It seems that OVS was syncing its own routing table with the kernel 
routing table. Since we were pushing 3x600k routes into kernel it 
triggered a constant flow of events for OVS. This in turn led to OVS 
running on 100% CPU.

We've managed to suppress the functionality by applying the attached 
patch. OVS is running smooth now.

Best regards,


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