[dpdk-dev] [RFC 17.08] Flow classification library

[Ferruh Yigit]

On 4/21/2017 11:38 AM, Gaëtan Rivet wrote:
> Hi Ferruh,
> 
> On Thu, Apr 20, 2017 at 07:54:47PM +0100, Ferruh Yigit wrote:
>> DPDK works with packets, but some network administration tools works based on
>> flow information.
>>
>> This library is suggested to provide helper APIs to convert packet based
>> information to the flow records. Library header file has more comments on
>> how library works and provided APIs.
>>
>> Packets to flow conversion will cause performance drop, that is why this
>> conversion can be enabled and disabled dynamically by application.
>>
>> Initial implementation in mind is to provide support for IPFIX metering process
>> but library planned to be as generic as possible. And flow information provided
>> by this library is missing to implement full IPFIX features, but this is planned
>> to be initial step.
>>
> 
> In order to be generic, would it not be interesting to specify the flow
> as a generic rte_flow_item list? Some specific IPFIX items are not
> expressed currently in rte_flow (e.g. packet size), but they could be added.
> 
> This library could consist in an rte_flow_item to IPFIX translation.

Agreed, it would be better to be able to use rte_flow, but I am not sure
if rte_flow will be enough for this case.

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.

> 
> The inverse approach could be used, but seems backward to me. It makes
> more sense to support DPDK idioms and open them to standards by
> proper APIs than including standards in internals and introduce
> translation layers between DPDK components.
> 
>> It is possible to define flow with various flow keys, but currently only one
>> type of flow defined in the library, which is more generic, and it offloads
>> fine grained flow analysis to the application. Library enables expanding for
>> other flow types.
>>
> 
> I'm not sure I understand the purpose of this flow key, generic
> is too general of a hint to define the possible cases.
> 
> However, my intuition is that the flow type describe a filter to
> restrict the flow classification to specific patterns instead of all
> supported ones.

Yes, that is the intention. User can define flow by key. And IPFIX
supports many flow features, that is missing right now.

> 
> This library thus resembles using the action RTE_FLOW_ACTION_TYPE_COUNT, then
> retrieved using rte_flow_query_count. The rte_flow_item aggregated with
> the rte_flow_query_count structure could be sufficient to derive IPFIX
> meters?

For counting, COUNT action looks like good candidate, it looks like it
is hard to build flow classification functionality completely on top of
rte_flow, but rte_flow can be used when appropriate like this case.

> 
> An application could then use this data for its IPFIX support.
> 
>> It will be more beneficial to shape this library to cover more use cases, please
>> feel free to comment on possible other use case and desired functionalities.
>>
>> Thanks,
>> ferruh
>>
>> cc: John McNamara <john.mcnamara at intel.com>
>> cc: Maryam Tahhan <maryam.tahhan at intel.com>
>>
>> Ferruh Yigit (1):
>>  flow_classify: add librte_flow_classify library
>>
>> config/common_base                                 |   5 +
>> doc/api/doxy-api-index.md                          |   1 +
>> doc/api/doxy-api.conf                              |   1 +
>> doc/guides/rel_notes/release_17_05.rst             |   1 +
>> lib/Makefile                                       |   2 +
>> lib/librte_flow_classify/Makefile                  |  50 +++++
>> lib/librte_flow_classify/rte_flow_classify.c       |  34 ++++
>> lib/librte_flow_classify/rte_flow_classify.h       | 202 +++++++++++++++++++++
>> .../rte_flow_classify_version.map                  |  10 +
>> 9 files changed, 306 insertions(+)
>> create mode 100644 lib/librte_flow_classify/Makefile
>> create mode 100644 lib/librte_flow_classify/rte_flow_classify.c
>> create mode 100644 lib/librte_flow_classify/rte_flow_classify.h
>> create mode 100644 lib/librte_flow_classify/rte_flow_classify_version.map
>>
>> -- 
>> 2.9.3
>>
>