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From: Jerin Jacob <jerinjacobk@gmail.com>
To: Andrey Vesnovaty <andrey.vesnovaty@gmail.com>
Cc: Thomas Monjalon <thomas@monjalon.net>, dpdk-dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC v2 0/1] add flow action context API
Date: Tue, 30 Jun 2020 15:22:21 +0530
Message-ID: <CALBAE1NOzb4WKVdkS2a299eK_zE2j6aMsaQ2Crn+B-Q=uWz2Lw@mail.gmail.com> (raw)
In-Reply-To: <CAOwx9SvXXamEZ+XA68kPQmZVQmUVG2ELsVJ_WNgRhRu4c=3KnQ@mail.gmail.com>

On Mon, Jun 29, 2020 at 3:52 PM Andrey Vesnovaty
<andrey.vesnovaty@gmail.com> wrote:
>
>
>
> On Sun, Jun 28, 2020 at 4:42 PM Jerin Jacob <jerinjacobk@gmail.com> wrote:
>>
>> On Sun, Jun 28, 2020 at 2:14 PM Andrey Vesnovaty
>> <andrey.vesnovaty@gmail.com> wrote:
>> >
>> > Hi
>> >
>> > On Fri, Jun 26, 2020 at 2:44 PM Jerin Jacob <jerinjacobk@gmail.com> wrote:
>> >>
>> >> On Sat, Jun 20, 2020 at 7:02 PM Andrey Vesnovaty
>> >> <andrey.vesnovaty@gmail.com> wrote:
>> >> >
>> >> > Hi, and thanks a lot for your RFC v1 comments.
>> >> >
>> >> > RFC v2 emphasize the intent for sharing the flow action:
>> >> > * The term 'action context' was unclear and replaced with
>> >> >    'shared action'.
>> >> > * RFC v2 subject became 'add flow shared action API'.
>> >> > * all proposed APIs renamed according the above.
>> >> >
>> >> > The new shared action is an independent entity decoupled from any flow
>> >> > while any flow can reuse such an action. Please go over the RFC
>> >> > description, it was almost entirely rewritten.
>> >> >
>> >> > @Jerin Jacob:
>> >> > Thanks again for your comments, it made me admit that v1 description was
>> >> > incomplete & unclear.  I hope v2 will be better at least in terms of
>> >> > clarity.
>> >>
>> >> The public API and its usage is very clear. Thanks for this RFC.
>> >
>> >
>> > My pleasure.
>> >>
>> >>
>> >> I think, RFC v2 still not addressing the concern raised in the
>> >> http://mails.dpdk.org/archives/dev/2020-June/169296.html.
>> >>
>> >> Since MLX hardware has an HW based shared object it is fine to have
>> >> public API based on that level of abstraction.
>> >> But at the PMD driver level we need to choose the correct abstraction
>> >> to support all PMD and support shared object scheme if possible.
>> >>
>> >> I purpose to introduce something below or similar
>> >>             int (*action_update)
>> >>                 (struct rte_eth_dev *,
>> >>                   struct rte_flow *flow,
>> >>                  const struct rte_flow_action [],
>> >>                  struct rte_flow_error *);
>> >
>> > Where this callback suppose to belong (struct rte_flow_ops)?
>>
>> Yes.
>>
>> > How should it be implemented by PMD?
>>
>> See below,
>>
>> > Is it about shared action and if "yes" why there is 'flow' argument?
>>
>> flow holds the "pattern" and "action" data as PMD specific handle.
>> So PMD, implementation can just change that action if it gets the PMD
>> specific handle.
>>
>>
>> >>
>> >>
>> >> in addition to: shared_action_create, shared_action_destroy,
>> >> shared_action_update, shared_action_query
>> >>
>> >> Have generic implementation of above, if action_update callback is not
>> >> NULL.
>> >
>> > "is not NULL" -> "is NULL"?
>>
>> Yes. When it is NULL.
>
>
> Jerin, few clarifications regarding generic implementation of shared action:
> Based on this conversation I'm assuming that generic implementation supposed to be something like:
> For each flow using some shared action:
> call ops-> action_update()
> If the assumption above correct:
> 1. taking into account that shared_action_update() is atomic, how can this deal with partial success: some flows may fail validation - should it:
>   1.1.lock all flows
>   1.2.validate all flows
>   1.3.update all flows
>   1.4. unlock

Yes.

> 2. action_update callback is PMD specific & if it's unsupported there is no support for shared action any way

Yes.

> Please address the issues above

>
>> >
>> >>
>> >> So that, it can work all PMDs and to
>> >> avoid the duplication of "complex" shared session management code.
>> >
>> > Do you mean shared action in use by multiple flows by "shared session"?
>>
>> Yes.
>
> Common 'shared session' management code:
> - can be reduced to atomic usage counter
> - maintaining list of flow using shared action expected to impact performance & not necessary for all PMD specific implementations
> Access to other shared resources hard to generalize because:
> - for some PMDs mutual exclusion is HW feature & no need to protect it in SW
> - for others there may be multiple resources & access to each one protected by different mechanism

The general callback you can assume, it supports only action_update
based callback.
If PMD has mutual exclusion HW feature then it can override the
function pointers.



> An observation related to action_update callback:
> If replaced (updated) action was shared then the flow won't be influenced any more by updates or removed shared action.

  reply	other threads:[~2020-06-30  9:52 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20  9:18 [dpdk-dev] [RFC] " Andrey Vesnovaty
2020-06-03 10:02 ` Thomas Monjalon
2020-06-04 11:12   ` Andrey Vesnovaty
2020-06-04 17:23     ` Thomas Monjalon
2020-06-05  8:30       ` Bruce Richardson
2020-06-05  8:33         ` Thomas Monjalon
2020-06-03 10:53 ` Jerin Jacob
2020-06-04 11:25   ` Andrey Vesnovaty
2020-06-04 12:36     ` Jerin Jacob
2020-06-04 15:57       ` Andrey Vesnovaty
2020-06-09 16:01         ` Jerin Jacob
2020-06-20 13:32           ` [dpdk-dev] [RFC v2 0/1] " Andrey Vesnovaty
2020-06-22 15:22             ` Thomas Monjalon
2020-06-22 17:09               ` Andrey Vesnovaty
2020-06-26 11:44             ` Jerin Jacob
2020-06-28  8:44               ` Andrey Vesnovaty
2020-06-28 13:42                 ` Jerin Jacob
2020-06-29 10:22                   ` Andrey Vesnovaty
2020-06-30  9:52                     ` Jerin Jacob [this message]
2020-07-01  9:24                       ` Andrey Vesnovaty
2020-07-01 10:34                         ` Jerin Jacob
2020-06-20 13:32           ` [dpdk-dev] [RFC v2 1/1] add flow shared action API Andrey Vesnovaty
2020-07-02  0:24             ` Stephen Hemminger
2020-07-02  7:20               ` Ori Kam
2020-07-02  8:06                 ` Andrey Vesnovaty

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