Re: [dpdk-dev] [PATCH v4 0/6] Flow entites behavior on port restart

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

On 10/26/2021 12:46 PM, Ferruh Yigit wrote:
> On 10/21/2021 7:34 AM, Dmitry Kozlyuk wrote:
>> It is unspecified whether flow rules and indirect actions are kept
>> when a port is stopped, possibly reconfigured, and started again.
>> Vendors approach the topic differently, e.g. mlx5 and i40e PMD
>> disagree in whether flow rules can be kept, and mlx5 PMD would keep
>> indirect actions. In the end, applications are greatly affected
>> by whatever contract there is and need to know it.
>>
>> Applications may wish to restart the port to reconfigure it,
>> e.g. switch offloads or even modify queues.
>> Keeping rte_flow entities enables application improvements:
>> 1. Since keeping the rules across restart comes with the ability
>>     to create rules before the device is started. This allows
>>     to have all the rules created at the moment of start,
>>     so that there is no time frame when traffic is coming already,
>>     but the rules are not yet created (restored).
>> 2. When a rule or an indirect action has some associated state,
>>     such as a counter, application saves the need to keep
>>     additional state in order to cope with information loss
>>     if such an entity would be destroyed.
>>
>> It is proposed to advertise capabilities of keeping flow rules
>> and indirect actions (as a special case of shared object)
>> using a combination of ethdev info and rte_flow calls.
>> Then a bug is fixed in mlx5 PMD that prevented indirect RSS action
>> from being kept, and the driver starts advertising the new capability.
>>
>> Prior discussions:
>> 1) http://inbox.dpdk.org/dev/20210727073121.895620-1-dkozlyuk@nvidia.com/
>> 2) http://inbox.dpdk.org/dev/20210901085516.3647814-1-dkozlyuk@nvidia.com/
>>
>> v4:  1. Fix rebase conflicts (CI).
>>       2. State rule behavior when a port is not started or stopped (Ori).
>>       3. Improve wording on rule features, add examples (Andrew).
>>       4. State that rules/actions that cannot be kept while other can be
>>          must be destroyed by the application (Andrew/Ori).
>>       5. Add rationale to the cover letter (Andrew).
>>
>> Dmitry Kozlyuk (6):
>>    ethdev: add capability to keep flow rules on restart
>>    ethdev: add capability to keep shared objects on restart
>>    net: advertise no support for keeping flow rules
>>    net/mlx5: discover max flow priority using DevX
>>    net/mlx5: create drop queue using DevX
>>    net/mlx5: preserve indirect actions on restart
>>
> 
> Requesting review from PMD maintainers.
> 
> Since this patch tries to define behavior on keeping/flushing flow rules
> after port stop/start/configure, better to get more feedback from various
> vendors, please review/comment on patch so that we can get it for -rc2.
> 
> If there is no comment the patch can go in as it is for -rc2.
> 

Last review call before merge.