[ovs-dev] 答复: How can we improve veth and tap performance in OVS DPDK?

Yi Yang (杨燚)-云服务集团 yangyi01 at inspur.com
Wed Jul 31 00:44:09 UTC 2019


Thanks Ilya, it works after disable tx offload, the performance is indeed very poor, about one tenth of ovs kernel. This is a very very strong warning for us, I strongly suggest ovs document should tell ovs DPDK users the truth in bold word.

For ovn, last year, the information I got is ovn can't support VXLAN, is it true so far? In my mind, GENEVE is worse than VXLAN as far as the performance is concerned.

-----邮件原件-----
发件人: Ilya Maximets [mailto:i.maximets at samsung.com] 
发送时间: 2019年7月30日 0:18
收件人: ovs-dev at openvswitch.org; Yi Yang (杨燚)-云服务集团 <yangyi01 at inspur.com>
主题: Re: [ovs-dev] How can we improve veth and tap performance in OVS DPDK?



On 29.07.2019 19:07, Ilya Maximets wrote:
>> Hi, all
>> We’re trying OVS DPDK in openstack cloud, but a big warn makes us hesitate.
>> Floating IP and qrouter use tap interfaces which are attached into 
>> br-int, SNAT also should use similar way, so OVS DPDK will impact on 
>> VM network performance significantly, I believe many cloud providers 
>> have deployed OVS DPDK, my questions are:
>>
>> 1.       Do we have some known ways to improve this?
> 
> As RedHat OSP guide suggests, you could use any SDN controller (like 
> OpenDayLight) or, alternatively, you could use OVN as a network provider for OpenStack.
> This way all the required functionality will be handled by the 
> OpenFlow rules inside OVS without necessity to send traffic over veths and taps to Linux Kernel.
> 
>> 2.       Is there any existing effort for this? Veth in kubernetes should
>> have the same performance issue in OVS DPDK case.
> 
> It makes no sense right now to run OVS-DPDK on veth pairs in Kubernetes.
> The only benefit from OVS-DPDK in K8s might be from using 
> virtio-vhost-user

I meant virtio-user ports.

> ports instead of veths for container networking. But this is not implemented.
> Running DPDK apps inside K8s containers has a lot of unresolved issues right now.
> 
> One approach that could improve performance of veths and taps in the 
> future is using AF_XDP sockets which are supported in OVS now. But 
> AF_XDP doesn't work properly for virtual interfaces (veths, taps) yet due to issues in Linux Kernel.
> 
>>
>> I also found a very weird issue. I added two veth pairs into ovs 
>> bridge and ovs DPDK bridge, for ovs case, iperf3 can work well, but 
>> it can’t for OVS DPDK case, what’s wrong.
> 
> This is exactly same issue as we already discussed previously. Disable 
> tx offloading on veth pairs and everything will work.
> 
> Best regards, Ilya Maximets.
> 
> 


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