Re: [RFC 17.08] flow_classify: add librte_flow_classify library

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 5/17/2017 5:38 PM, Gaëtan Rivet wrote:
> Hi Ferruh,

Hi Gaetan,

> 
> On Wed, May 17, 2017 at 05:02:50PM +0100, Ferruh Yigit wrote:
>> On 5/17/2017 3:54 PM, Ananyev, Konstantin wrote:
>>> Hi Ferruh,
>>> Please see my comments/questions below.
>>
>> Thanks for review.
>>
>>> Thanks
>>> Konstantin
>>
>> <...>
>>
>>> I think it was discussed already, but I still wonder why rte_flow_item can't be used for that approach?
>>
>> Missed this one:
>>
>> Gaëtan also had same comment, copy-paste from other mail related to my
>> concerns using rte_flow:
>>
>> "
>> rte_flow is to create flow rules in PMD level, but what this library
>> aims to collect flow information, independent from if underlying PMD
>> implemented rte_flow or not.
>>
>> So issues with using rte_flow for this use case:
>> 1- It may not be implemented for all PMDs (including virtual ones).
>> 2- It may conflict with other rte_flow rules created by user.
>> 3- It may not gather all information required. (I mean some actions
>> here, count like ones are easy but rte_flow may not be so flexible to
>> extract different metrics from flows)
>> "
> 
> There are two separate elements to using rte_flow in this context I think.
> 
> One is the use of the existing actions, and as you say, this makes the
> support of this library dependent on the rte_flow support in PMDs.
> 
> The other is the expression of flows through a shared syntax. Using
> flags to propose presets can be simpler, but will probably not be flexible
> enough. rte_flow_items are a first-class citizen in DPDK and are
> already a data type that can express flows with flexibility. As
> mentioned, they are however missing a few elements to fully cover IPFIX
> meters, but nothing that cannot be added I think.
> 
> So I was probably not clear enough, but I was thinking about
> supporting rte_flow_items in rte_flow_classify as the possible key
> applications would use to configure their measurements. This should not
> require rte_flow supports from the PMDs they would be using, only
> rte_flow_item parsing from the rte_flow_classify library.
> 
> Otherwise, DPDK will probably end up with two competing flow
> representations. Additionally, it may be interesting for applications
> to bind these data directly to rte_flow actions once the
> classification has been analyzed.

Thanks for clarification, I see now what you and Konstantin is proposing.

And yes it makes sense to use rte_flow to define flows in the library, I
will update the RFC.

Thanks,
ferruh