Re: [dpdk-dev] [PATCH] add flow shared action API

[Jerin Jacob <jerinjacobk@gmail.com>]

On Mon, Jul 6, 2020 at 7:02 PM Andrey Vesnovaty
<andrey.vesnovaty@gmail.com> wrote:
>
> Hi, Jerin.

Hi Ori and Andrey,


>
> Please see below Ori's suggestion below to implement your rte_flow_action_update() idea
> with some API changes of rte_flow_shared_action_xxx API changes.
>
> On Mon, Jul 6, 2020 at 3:28 PM Ori Kam <orika@mellanox.com> wrote:
>>
>> Hi Jerin,
>>
>> > -----Original Message-----
>> > From: Jerin Jacob <jerinjacobk@gmail.com>
>> > Sent: Monday, July 6, 2020 12:00 PM
>> > Subject: Re: [dpdk-dev] [PATCH] add flow shared action API
>> >
>> > On Sun, Jul 5, 2020 at 3:56 PM Ori Kam <orika@mellanox.com> wrote:
>> > >
>> > > Hi Jerin,
>> > > PSB,
>> > >
>> > > Thanks,
>> > > Ori
>> > >
>> > > > -----Original Message-----
>> > > > From: Jerin Jacob <jerinjacobk@gmail.com>
>> > > > Sent: Saturday, July 4, 2020 3:33 PM
>> > > > dpdk-dev <dev@dpdk.org>
>> > > > Subject: Re: [dpdk-dev] [PATCH] add flow shared action API
>> > > >
>> > > > On Sat, Jul 4, 2020 at 3:40 PM Andrey Vesnovaty
>> > > > <andrey.vesnovaty@gmail.com> wrote:
>> > > > >
>> > > > >
>> > > > > Thanks,
>> > > > >
>> > > > > Andrey Vesnovaty
>> > > > > (+972)526775512 | Skype: andrey775512
>> > > > >
>> > >
>> > >
>> > > [..Nip ..]
>> > >
>> > > > > I need to mention the locking issue once again.
>> > > > > If there is a need to maintain "shared session" in the generic rte_flow
>> > layer
>> > > > all
>> > > > > calls to flow_create() with shared action & all delete need to take
>> > > > sharedsession
>> > > > > management locks at least for verification. Lock partitioning is also bit
>> > > > problematic
>> > > > > since one flow may have more than one shared action.
>> > > >
>> > > > Then, I think better approach would be to introduce
>> > > > rte_flow_action_update() public
>> > > > API which can either take "const struct rte_flow_action []" OR shared
>> > > > context ID, to cater to
>> > > > both cases or something on similar lines. This would allow HW's
>> > > > without have  the shared context ID
>> > > > to use the action update.
>> > >
>> > > Can you please explain your idea?
>> >
>> > I see two types of HW schemes supporting action updates without going
>> > through call `rte_flow_destroy()` and call `rte_flow_create()`
>> > - The shared HW action context feature
>> > - The HW has "pattern" and "action" mapped to different HW objects and
>> > action can be updated any time.
>> > Other than above-mentioned RSS use case, another use case would be to
>> > a) create rte_flow and set the action as DROP (Kind of reserving the HW object)
>> > b) Update the action only when the rest of the requirements ready.
>> >
>> > Any API schematic that supports both notions of HW is fine with me.
>> >
>> I have an idea if the API will be changed to something like this,
>> Rte_flow_shared_action_update(uint16_port port, rte_shared_ctx *ctx, rte_flow_action *action, error)
>> This will enable the application to send a different action than the original one to be switched.
>> Assuming the PMD supports this.
>> Does it answer your concerns?
>
>
> This allows both:
> 1. Update action configuration
> 2. Replace action by some other action
> For 2 pure software implementation may carate shred action (that can be shared
> with one flow only, depends on PMD) and later on rte_flow_shared_action_update may replace this
> action with some other action by handle returned from rte_flow_shared_action_create
> Doesign between 1 and 2 is per PMD.

struct rte_flow * object holds the driver representation of the
pattern + action.
So in order to update the action, we would need struct rte_flow * in API.

I think, simple API change would be to accommodate "rte_shared_ctx
*ctx, rte_flow_action *action" modes
without introducing the emulation for one or other mode, will be.

enum rte_flow_action_update_type {
              RTE_FLOW_ACTION_UPDATE_TYPE_SHARED_ACTION,
              RTE_FLOW_ACTION_UPDATE_TYPE_ACTION,
};

struct rte_flow_action_update_type_param {
         enum rte_flow_action_update_type type;
         union {
                     struct rte_flow_action_update_type_shared_action_param {
                                rte_shared_ctx *ctx;
                      } shared_action;
                      struct rte_flow_action_update_type_shared_action_param {
                                rte_flow *flow,
                                 rte_flow_action *action;
                      } action;
         }
}

rte_flow_action_update(uint16_port port, struct
rte_flow_action_update_type_param  *param, error)

>
>>
>> >
>> > > As I can see if we use the flow_action array it may result in bugs.
>> > > For example, the application created two flows with the same RSS (not using
>> > the context)
>> > > Then he wants to change one flow to use different RSS, but the result will that
>> > both flows
>> > > will be changed.
>> >
>> > Sorry. I don't quite follow this.
>> >
>> I was trying to show that there must be some context. But I don’t think this is relevant to
>> your current ideas.
>>
>> > > Also this will enforce the PMD to keep track on all flows which will have
>> > memory penalty for
>> > > some PMDs.
>>
>> Best,
>> Ori
>
>
> Thanks,
> Andrey