On 01/16/2019 10:21 AM, Thomas Monjalon wrote:
> 16/01/2019 11:03, Ophir Munk:
>> Hi Kevin and thank you for your comments.
>> Please see inline...
>>
>> From: Kevin Traynor <[email protected]>
>>> On 01/15/2019 09:47 AM, Ophir Munk wrote:
>>>> Dpdk port representors were introduced in dpdk versions 18.xx.
>>>> Prior to port representors there was a one-to-one relationship between
>>>> an rte device (e.g. PCI bus) and an eth device (referenced as dpdk
>>>> port id in OVS). With port representors the relationship becomes
>>>> one-to-many rte device to eth devices.
>>>> For example in [3] there are two devices (representors) using the same
>>>> PCI physical address 0000:08:00.0: "0000:08:00.0,representor=[3]" and
>>>> "0000:08:00.0,representor=[5]".
>>>> This commit handles the new one-to-many relationship. For example,
>>>> when one of the device port representors in [3] is closed - the PCI
>>>> bus cannot be detached until the other device port representor is
>>>> closed as well. OVS remains backward compatible by supporting dpdk
>>>> legacy PCI ports which do not include port representors.
>>>> Dpdk port representors related commits are listed in [1]. Dpdk port
>>>> representors documentation appears in [2]. A sample configuration
>>>> which uses two representors ports (the output of "ovs-vsctl show"
>>>> command) is shown in [3].
>>>>
>>>
>>> Hi Ophir, I had a scan through and there isn't any documentation/examples
>>> for this outside the commit message. I think a user would need something
>>> basic, or at least reference to know that this exists and how to use it.
> 
> The user needs to know the DPDK syntax to reference DPDK ports.
> This documentation should be provided by DPDK.
> We don't have a doc summarizing all at the moment (I will work on it).
> I suggest you collect URLs for pieces of docs and list them in OVS doc
> about dpdk-devargs.
> 

Yes, an OVS user will look at OVS docs (hopefully) but probably not
commit messages or C code. Also, the reference has some nice testpmd
examples. A simple OVS example would be nice, perhaps a section in
ovs/Documentation/topics/dpdk/phy.rst with an example and links?

>>>> [2]
>>>> doc/guides/prog_guide/switch_representation.rst
>>>>
>>
>> I now realize that the reference given in [2] requires downloading DPDK.
>> In v6 I will update it with a new reference:
>>
>> https://doc.dpdk.org/guides-18.08/prog_guide/switch_representation.html
> 
> No need to specify a version:
> https://doc.dpdk.org/guides/prog_guide/switch_representation.html
> 

Maybe better to specify 18.11 in case something is added/removed in
later DPDK.

>> which includes abundant of documentation/examples. 
>> Can you please have a look and let me know if it is sufficient, or maybe you 
>> have other ideas where more documentation should be added.
> 
> There is also some documentation for representor syntax:
> https://doc.dpdk.org/guides/prog_guide/poll_mode_drv.html#ethernet-device-standard-device-arguments
> 
> But honestly, I doubt you need to talk about representors in this patch.
> The change is to support multi-ports device generally.

ok, then just need a way to tell OVS user that the new functionality is
existing.

> The representor ports are just a use case of multi-ports.
> Other use cases:
>       https://doc.dpdk.org/guides/nics/mlx4.html#implementation-details
>       https://doc.dpdk.org/guides/nics/cxgbe.html#limitations
> For these use cases, we can use the mac= argument in devargs.
> 
> 

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