[ovs-discuss] OVS DPDK NUMA pmd assignment question for physical port

王志克 wangzhike at jd.com
Wed Sep 6 02:18:40 UTC 2017


Hi All,

I read below doc about pmd assignment for physical port. I think the limitation “on the same NUMA node” may be not efficient.

http://docs.openvswitch.org/en/latest/intro/install/dpdk/
DPDK Physical Port Rx Queues¶<http://docs.openvswitch.org/en/latest/intro/install/dpdk/#dpdk-physical-port-rx-queues>

$ ovs-vsctl set Interface <DPDK interface> options:n_rxq=<integer>

The above command sets the number of rx queues for DPDK physical interface. The rx queues are assigned to pmd threads on the same NUMA node in a round-robin fashion.
Consider below case:

One host has one PCI NIC on NUMA node 0, and has 4 VMs, which spread in NUMA node 0 and 1. There are multiple rx queues configured on the physical NIC. We configured 4 pmd (two cpu from NUMA node0, and two cpu from node 1). Since the physical NIC locates on NUMA node0, only pmds on same NUMA node can poll its rxq. As a result, only two cpu can be used for polling physical NIC.

If we compare the OVS kernel mode, there is no such limitation.

So question:
should we remove “same NUMA node” limitation fro physical port rx queues? Or we have other options to improve the performance for this case?

Br,
Wang Zhike

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