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From: Thomas Monjalon <thomas@monjalon.net>
To: Ferruh Yigit <ferruh.yigit@amd.com>,
	Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
	Yuying Zhang <yuying.zhang@intel.com>
Cc: Rongwei Liu <rongweil@nvidia.com>,
	matan@nvidia.com, viacheslavo@nvidia.com, orika@nvidia.com,
	Aman Singh <aman.deep.singh@intel.com>,
	dev@dpdk.org, rasland@nvidia.com, jerinj@marvell.com
Subject: Re: [PATCH v7] ethdev: add special flags when creating async transfer table
Date: Thu, 02 Feb 2023 12:29:28 +0100	[thread overview]
Message-ID: <12425652.O9o76ZdvQC@thomas> (raw)
In-Reply-To: <0f546992-dbd8-6d86-3d87-015a3dae98ee@oktetlabs.ru>

02/02/2023 10:21, Andrew Rybchenko:
> On 2/1/23 16:48, Thomas Monjalon wrote:
> > 01/02/2023 12:38, Andrew Rybchenko:
> >> On 2/1/23 14:18, Thomas Monjalon wrote:
> >>> 01/02/2023 12:10, Andrew Rybchenko:
> >>>> On 2/1/23 13:58, Thomas Monjalon wrote:
> >>>>> 01/02/2023 11:17, Andrew Rybchenko:
> >>>>>> On 1/18/23 19:18, Thomas Monjalon wrote:
> >>>>>>> 18/01/2023 08:28, Andrew Rybchenko:
> >>>>>>>> On 11/14/22 14:59, Rongwei Liu wrote:
> >>>>>>>>> In case flow rules match only one kind of traffic in a flow table,
> >>>>>>>>> then optimization can be done via allocation of this table.
> >>>>>>>>> Such optimization is possible only if the application gives a hint
> >>>>>>>>> about its usage of the table during initial configuration.
> >>>>>>>>>
> >>>>>>>>> The transfer domain rules may process traffic from wire or vport,
> >>>>>>>>> which may correspond to two kinds of underlayer resources.
> >>>>>>>>> That's why the first two hints introduced in this patch are about
> >>>>>>>>> wire and vport traffic specialization.
> >>>>>>>>> Wire means traffic arrives from the uplink port while vport means
> >>>>>>>>> traffic initiated from VF/SF.
> >>>>>>>>>
> >>>>>>>>> There are two possible approaches for providing the hints.
> >>>>>>>>> Using IPv4 as an example:
> >>>>>>>>> 1. Use pattern item in both template table and flow rules.
> >>>>>>>>>
> >>>>>>>>>         pattern_template: pattern ANY_VPORT / eth / ipv4 is 1.1.1.1 / end
> >>>>>>>>>         async flow create: pattern ANY_VPORT / eth / ipv4 is 1.1.1.2 / end
> >>>>>>>>>
> >>>>>>>>>         "ANY_VPORT" needs to be present in each flow rule even if it's
> >>>>>>>>>         just a hint. No value to match because matching is already done by
> >>>>>>>>>         IPv4 item.
> >>>>>>>>>
> >>>>>>>>> 2. Add special flags into table_attr.
> >>>>>>>>>
> >>>>>>>>>         template_table 0 create table_id 0 group 1 transfer vport_orig
> >>>>>>>>>
> >>>>>>>>> Approach 1 needs to specify the pattern in each flow rule which wastes
> >>>>>>>>> memory and is not user friendly.
> >>>>>>>>> This patch takes the 2nd approach and introduces one new member
> >>>>>>>>> "specialize" into rte_flow_table_attr to indicate possible flow table
> >>>>>>>>> optimization.
> >>>>>>>>
> >>>>>>>> The above description is misleading. It alternates options (1)
> >>>>>>>> and (2), but in fact (2) requires (1) as well.
> >>>>>>>
> >>>>>>> Yes the above description may be misleading
> >>>>>>> and it seems you are misleaded :)
> >>>>>>
> >>>>>> It is not my intention. If it is only my problem, I'm OK to
> >>>>>> step back.
> >>>>>
> >>>>> It's OK to explain and check everything is OK, no worries.
> >>>>> Thanks for reviewing.
> >>>>>
> >>>>>>> I will explain below why the option (2) doesn't require (1).
> >>>>>>> I think we should apply the same example to both cases to make it clear:
> >>>>>>>
> >>>>>>> 1. Use pattern item in both template table and flow rules:
> >>>>>>>
> >>>>>>>        template table 3 = transfer pattern ANY_VPORT / eth / ipv4 src is 255.255.255.255 / end
> >>>>>>>        flow rule = template_table 3 pattern ANY_VPORT / eth / ipv4 src is 1.1.1.1 / end
> >>>>>>>
> >>>>>>>        The pattern template 3 will be used only to match flows coming from vports.
> >>>>>>>        ANY_VPORT needs to be present in each flow rule.
> >>>>>>
> >>>>>> It looks like I lost something here. Why do we need to specify
> >>>>>> it in each flow rule if the matching is already fixed in
> >>>>>> template table?
> >>>>>
> >>>>> I think that's how template tables are designed.
> >>>>> Ori, please could you point us to the relevant documentation?
> >>>>>
> >>>>>>>        ANY_VPORT matching is redundant with IP src 1.1.1.1 because
> >>>>>>>        the user knows 1.1.1.1 is the IP of a vport.
> >>>>>>
> >>>>>> What should happen if a packet with src IP 1.1.1.1 comes from
> >>>>>> the wire? Almost anything could come from network.
> >>>>>
> >>>>> It a packet comes from a wired port AND
> >>>>> the PMD did an optimization based on this hint,
> >>>>> then the packet could be not matched.
> >>>>
> >>>> So, the hint changes matching results and therefore becomes
> >>>> a strange (extra) matching criteria under specific
> >>>> circumstance. It sounds bad.
> >>>
> >>> In this case, the user made a wrong assumption.
> >>> If the user does not do a mistake, the behavior should be the same
> >>> whether the hint is used or ignored.
> >>>
> >>>> So, good application must use
> >>>> real (always) matching criteria when composing flow rules.
> >>>
> >>> Of course, nothing replaces matching criteria.
> >>>
> >>>> So, RTE flow API should provide a way to write a good
> >>>> application without extra pain.
> >>>> That's why I'm saying that (2) requires (1) anyway.
> >>>
> >>> I don't follow this sentence.
> >>> If you mean with hint, flow matching is still required, then yes,
> >>> this is what I emphasized in my rewrite of the case (2) below.
> >>>
> >>>> It does not say that hint is not required at all.
> >>>> It is still useful for resources usage optimization if
> >>>> application knows how it is going to use particular table.
> >>>
> >>> Yes, that's an optional optimization.
> >>> It should not change the rules,
> >>> and it should not change the functional behavior
> >>> if the user does not do mistakes.
> >>
> >> So, we basically agree on the topic, but my goal here is a bit
> >> bigger. Make it easier for a user to avoid mistakes. May be it
> >> is stupid goal :) and all efforts are vain.
> >> If we have a match item with similar functionality it would be
> >> easy to just put it into a pattern. Otherwise, it could be
> >> complicated, have high chances to be skipped and rely on
> >> implicit matching criteria imposed by the hint on the HW
> >> which takes it into account.
> > 
> > We may highlight in the doc that the functional behaviour must not rely
> > on the hints. It is only optional optimization and effects may vary
> > with differents driver.
> > What do you think? I don't know what else to do about user mistakes :)
> 
> As I said - add corresponding pattern items.

I think I get it now.
You suggest to have pattern items for VPORT and PHY_PORT,
so the user won't be tempted to use hint for such matching?
We used to have RTE_FLOW_ITEM_TYPE_PHY_PORT, we could think about it.

> Anyway, hint itself is OK and makes sense. Hopefully
> documentation highlights that pattern match is required.

Yes we did an effort to highlight what are hints in the last version.

> If so,
> 
> Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>




  reply	other threads:[~2023-02-02 11:29 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-07  2:40 [PATCH v1] ethdev: add direction info when creating the " Rongwei Liu
2022-09-11  8:22 ` Ori Kam
2022-09-12 16:57 ` Ivan Malov
2022-09-13 13:46   ` Rongwei Liu
2022-09-13 14:33     ` Ivan Malov
2022-09-14  5:16       ` Rongwei Liu
2022-09-14  7:32         ` Ivan Malov
2022-09-14 10:17           ` Rongwei Liu
2022-09-14 15:18             ` Ivan Malov
2022-09-14 21:02               ` Thomas Monjalon
2022-09-15  0:58               ` Rongwei Liu
2022-09-15  7:47                 ` Ivan Malov
2022-09-15  8:18                   ` Thomas Monjalon
2022-09-15  9:42                     ` Ivan Malov
2022-09-15  8:48                   ` Rongwei Liu
2022-09-15 10:59                     ` Ivan Malov
2022-09-15 11:16                       ` Thomas Monjalon
2022-09-20  9:41                         ` Ori Kam
2022-09-20 12:45                           ` Ivan Malov
2022-09-20 13:59                             ` Ori Kam
2022-09-20 15:28                               ` Ivan Malov
2022-09-21  7:34                                 ` Ori Kam
2022-09-21  8:39                                   ` Andrew Rybchenko
2022-09-21  9:04                                   ` Ivan Malov
2022-09-21  9:40                                     ` Thomas Monjalon
2022-09-21 10:04                                       ` Andrew Rybchenko
2022-09-21 12:41                                         ` Ori Kam
2022-09-21 12:51                                           ` Morten Brørup
2022-09-22  7:39                                             ` Andrew Rybchenko
2022-09-22 10:06                                               ` Ori Kam
2022-09-22 10:31                                                 ` Andrew Rybchenko
2022-09-22 13:00                                                   ` Ori Kam
2022-09-23  7:25                                                     ` Andrew Rybchenko
2022-09-23 16:11                                                       ` Ori Kam
2022-09-22 12:43                                                 ` Ivan Malov
2022-09-22 14:46                                                   ` Ori Kam
2022-09-28  9:24       ` [PATCH v3] ethdev: add hint when creating async " Rongwei Liu
2022-10-04  8:31         ` Andrew Rybchenko
2022-11-04 10:42           ` [PATCH v4] ethdev: add special flags " Rongwei Liu
2022-11-04 10:44           ` Rongwei Liu
2022-11-08 11:39             ` Andrew Rybchenko
2022-11-08 11:47               ` Andrew Rybchenko
2022-11-08 13:29                 ` Thomas Monjalon
2022-11-08 14:38                   ` Andrew Rybchenko
2022-11-08 15:25                     ` Thomas Monjalon
2022-11-09  8:53                       ` Andrew Rybchenko
2022-11-09  9:03                         ` Thomas Monjalon
2022-11-09  9:36                           ` Andrew Rybchenko
2022-11-09 10:50                             ` Thomas Monjalon
2022-11-06 10:02           ` [PATCH v3] ethdev: add hint " Andrew Rybchenko
2022-11-07  1:58             ` Rongwei Liu
2022-11-08  9:19             ` Thomas Monjalon
2022-11-08  9:35               ` Andrew Rybchenko
2022-11-08 11:18                 ` Thomas Monjalon
2022-11-08 11:48                   ` Andrew Rybchenko
2022-11-14  8:47                     ` [PATCH v6] ethdev: add special flags " Rongwei Liu
2022-11-14 11:59                     ` [PATCH v7] " Rongwei Liu
2023-01-17 15:13                       ` Ferruh Yigit
2023-01-17 17:01                         ` Ferruh Yigit
2023-01-18  2:50                           ` Rongwei Liu
2023-01-18  7:30                         ` Andrew Rybchenko
2023-01-18  7:28                       ` Andrew Rybchenko
2023-01-18 16:18                         ` Thomas Monjalon
2023-02-01 10:17                           ` Andrew Rybchenko
2023-02-01 10:58                             ` Thomas Monjalon
2023-02-01 11:10                               ` Andrew Rybchenko
2023-02-01 11:18                                 ` Thomas Monjalon
2023-02-01 11:38                                   ` Andrew Rybchenko
2023-02-01 13:48                                     ` Thomas Monjalon
2023-02-02  9:21                                       ` Andrew Rybchenko
2023-02-02 11:29                                         ` Thomas Monjalon [this message]
2023-02-02 12:24                                           ` Andrew Rybchenko
2023-02-01 11:22                                 ` Ori Kam
2023-02-01 11:29                                   ` Andrew Rybchenko
2023-02-01 11:12                               ` Ori Kam
2023-02-01 11:20                                 ` Thomas Monjalon
2023-01-30  0:00                       ` Ivan Malov
2023-01-30  2:34                         ` Rongwei Liu
2023-01-30  7:40                           ` Ivan Malov
2023-01-30 14:49                             ` Rongwei Liu
2023-01-30 23:00                               ` Ivan Malov
2023-01-31  3:06                                 ` Rongwei Liu
2023-01-31  5:30                                   ` Ivan Malov
2023-01-31  6:14                                     ` Rongwei Liu
2023-02-01 10:12                                     ` Thomas Monjalon
2023-02-01 11:50                                       ` Ivan Malov
2023-02-01 13:37                                         ` Thomas Monjalon
2023-02-01 14:04                                           ` Ivan Malov
2023-02-01 14:23                                             ` Thomas Monjalon
2023-02-01 14:29                                             ` Ori Kam
2023-02-02 11:19                       ` [PATCH v8] ethdev: add optimization hints in flow template table Rongwei Liu
2023-02-02 11:33                         ` Thomas Monjalon
2023-02-08 23:19                           ` Ferruh Yigit
2022-11-09  8:11           ` [PATCH v5] ethdev: add special flags when creating async transfer table Rongwei Liu
2022-11-09  8:13           ` Rongwei Liu
2022-11-09  8:31             ` Thomas Monjalon

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