[ovs-discuss] OVS DPDK with no DPDK nics on NUMA 0

Stokes, Ian ian.stokes at intel.com
Tue Jan 17 14:44:44 UTC 2017


> This article https://software.intel.com/en-us/articles/using-open-vswitch-
> and-dpdk-with-neutron-in-devstack says: "If you have the NICs installed
> entirely on a NUMA Node other than 0, you will encounter a bug that will
> prevent correct OVS setup. You may wish to move your NIC device to a
> different PCIe slot."
> 
> Anyone know what this bug is, and is it in OVS-DPDK?  "correct OVS setup"
> suggests that it might just be a bug in the devstack script.

I think this bug is related to the fact that the ovs PMD coremask value defined in the local.conf is 0x4 by default, which is a cpu 3 on socket 0 in this case. If the NIC is attached to NUMA node 1 then it will fail to initialize I believe.

I think this is still an issue today for OVS-DPDK, but there are plans to enable cross numa pmd configurations (although one should note that there would be a performance penalty for crossing the numa nodes).

There is a work around mentioned in the guide under the 'Additional OVS/DPDK Options of Note', essentially you may change the pmd coremask to be a cpu on numa node 1.

Thanks
Ian



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