[ovs-dev] 答复: Ask for help about ovs datapath development

zhang hao zh_94 at outlook.com
Thu Oct 4 07:28:18 UTC 2018


Thanks for your suggestion. I have read the "Development" and "Implementation Details" in the FQAs, and that helps a lot.

Well, what I really want to do is that making the ovs become a real-time vswitch. And my primary idea is  to add a real-time datapath, which has higher priority of transmission than the other normal ones. To implement that, I plan to put the tstamp attributes of struct sk_buff into use, and add a new attribute to the sw_flow and sw_key the point out whether a  skb is a real-time packet or not. And if it is, it will be put into the real-time datapath.

So the main part I want to work in is the kernel space program of ovs. (I think so, maybe I am wrong) But what the "Development" of FQAs talk about is the user space program. luckily, in the Open vSwitch Datapath Development Guide, I found the explanation about"Flow Key Compatibility" helps, and it said that "If the kernel’s flow key includes more fields than the userspace version of the flow key, userspace can still set up a flow in the usual way, as long as it uses the kernel-provided flow key to do it." does that mean I need not modify the user space program? And if I just modify the kernel datapath, will the ovs become a real-time ovs, or run as usual just without error?


发件人: Numan Siddique <nusiddiq at redhat.com>
发送时间: 2018年10月3日 10:21
收件人: zh_94 at outlook.com
抄送: ovs-dev at openvswitch.org
主题: Re: [ovs-dev] Ask for help about ovs datapath development

On Wed, Oct 3, 2018 at 2:46 PM zhang hao <zh_94 at outlook.com<mailto:zh_94 at outlook.com>> wrote:

My name is Zhanghao and I am a student major in software engineering of Tsinghua university. I am learning SDN and very interested in ovs. I want to do some contribution to it but meet some difficulties.

To be exactly, I want to add a new kind of flow, which may need process specially. So I think it needs to add a new attribute in the flow key, a new sw_flow to the flow table and maybe add a new attribute to sw_flow itself, and a new type action. But I find the user space program of ovs is too large and difficult for me. Can I achieve my idea just by modify the code in the datapath folder?

I will be very grateful for any reply.


Hi zhanghao,

Take a look at the FAQ of openvswitch - http://docs.openvswitch.org/en/latest/faq/contributing/
This may help you.


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