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

[Ori Kam <orika@mellanox.com>]

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?

> 
> > 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