[ovs-discuss] what is multiq - and why is it required by ovs for dpdk vmnet3 interfaces?

Stokes, Ian ian.stokes at intel.com
Thu Jan 22 21:03:40 UTC 2015


> -----Original Message-----
> From: discuss [mailto:discuss-bounces at openvswitch.org] On Behalf Of David
> Evans
> Sent: Monday, January 12, 2015 3:01 PM
> To: discuss at openvswitch.org
> Subject: [ovs-discuss] what is multiq - and why is it required by ovs for dpdk
> vmnet3 interfaces?
> 
> Hi,
> 
> If I add vmnet3 dpdk compatible driver to ovs, I cannot use it in ovs because
> it requires multiq?
OVS has not been tested with with the vmnet3 driver (I assume you are using the vmxnet3-usermap.ko driver) so there is no guarantee that it will work without further modification to netdev-dpdk. 
> What does this mean?
Multiq is used to set the number of tx_queues and rx_queues for the dpdk interface in OVS. Usually these correspond to the number of cores the DPDK application has been launched with. netdev_set_multiq is called as standard as part of 'do_add_port' and ' dpif_netdev_pmd_set' in dpif-netdev.c. 

>From reading the documentation regarding  vmxnet3-usermap.ko you will have to make sure that the parameters used when loading the vmxnet3 driver will have to match those parameters used to launch the DPDK application (in this case ovs-vswitchd).
> Could I change it?
As pointed out above, it may be an issue relating to how the driver and application is setup but could also require a change to the netdev-dpdk code, as multiq is part and parcel of the DPDK application this may be difficult.
> Regards,
> 
> Dave.



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