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

[Andrey Vesnovaty <andrey.vesnovaty@gmail.com>]

Hi, Jerin.

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.


> >
> > > 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